Anyone who has spent even a little time on Internet forums is usually more than familiar with the rules of most of them, which can generally be summed up as follows:  "No spamming, no self-promotion links, and no personal attacks or obscenity".   Most forum threads can be categorized into a type.  There is the "big, deep, discussion" - not the most common on most forums.  
Then there is the long string of foolish one-liners - some  of which are funny, some of which are not, some of which are primarily back-and-forth between a small number of particpants.  The long string of meaningless one-liners may or may not be entertaining.  Sometimes, for the person not engaged in the back-and-forth these threads can be pretty boring.

There are also the "business-like" threads.  These are often in "knowledge-type" categories, and are threads which share "business-like" information - how to do one thing or another on the forum or the site, or information about "no-nonsense" matters online or off.  Then, too, there are the "hot-button-issues" discussions, often in politics or religion.  These discussions can include the more heated version of the "big, deep, discussion".  They can get contentious, and they can border on being hostile.  Even these, though, usually remain somewhat confined to the "flavor" of their nature, rather than veering off too far in a wild direction.

Most sites that offer forums make it clear that people not to make personal attacks, and that they are to use the forums as outlined in the guidelines.  Most of the time forum threads go along, ranging from light to business-like to serious, without ever straying too far from their purpose.  Once in a while, however, a thread will stray so far off it turns into an amazing study in human nature, forums, and any number of other things.   Whether the participants intend it or not, such threads become extremely entertaining and sometimes hilarious (even when anger is at the root of the veering off).   When humor hijacks a thread the only thing I ever feel guilty about is contributing to the straying away from a more serious original purpose of the thread.  When anger hijacks a thread I tend to feel guilty when I find myself laughing hysterically at how bizarre things turn, mostly because I know how sites frown on "nasty".   I don't approve of being nasty to other people on forums, and I know why guidelines always warn against it.  Still, the mix of comments from a wide range of personalities has a way of turning hijacked threads into a unique blend of humor, sarcasm, and any number of other things.    It always leave one wondering how, on Earth, things stray off as far as they do.  

I've realized that it is seldom on "hijacker" who pulls things off track.  Instead, it is one person who shifts the conversation off to the side, either a little or a lot.   It's as if that one person breaks the previous, consistent, line of conversation and seems to invite the posters who follow to do the same.  Maybe once the line of the conversation has been shifted over the person who follows is faced with having nothing to go by when it comes to his response.  Maybe, too, when people see the post that has shifted things off track it triggers some kind of response that amounts to getting the emotions ramped up just a little.

Generally, I behave pretty well on forums.  I am always struggling with the guilt of my tendency to be long-winded on subjects I see as serious.  I'm not the "hostile type", though, so when things get heated I'm more likely to try to discuss the situation back to civil, which is, I know, boring for a lot of people.  Then, too, I'm guilty of attempting to be funny but not being funny.  In spite of my general good manners, though, there was one time when I shifted a routine, business-like, thread off to the side; and the result was a thread that went so wacky people started to talk about how hilarious it all was.   Even an administrator weighed in and said it was "a hoot" and that she was going to send it around to the people in the office.   I'm generally not a "big, fun" person in a crowd.  (I can be a barrel of laughs with one or two people, but I'm pretty much a wallflower in a crowd).  I'll admit that I was pretty darned pleased with myself to think that I had gotten this hilarious thread going to the point it was.

It started with people discussing what bothered them about other people's writing.  There was one pet peeve after another listed.  Somewhat uncharacteristically, I decided to incorporate everyone's pet peeves into one post and hope people "got" what I was doing.  (There's nothing worse than trying to be funny and having nobody get it.)   Sure enough, the next poster got what I was doing and added his own version of the same thing.  One after another, people were building on the humor.  With so many different personalities, of course, each post was a kind of "out-of-the-blue" kind of surprise.  The color that a bunch of people can add to something is what makes knocked-off-the-track thread so entertaining.    As one person after another picked up on this particular thread I started to worry about "being responsible" for taking the previously business-like thread off into its wild and wacky direction.   Still, the posts kept coming, and the thing was getting funnier and funnier.  Sitting alone at my computer, and laughing so hard I couldn't catch my breath,  I felt like a leader (or sorts), a rebel (or sorts), an instigator (in a way), and (of course) an idiot.    I was amazed, though, at the way one person would "get" exactly what the previous one had done, and so smoothly pick up and bring the thread that much farther "down the road" to being hilarious.    A few pages into all the hijincks someone who wasn't quite able to pick up on what was happening knocked the funny thread off to the side yet again,  and little by little the thread was returned to its original (although un-funny) purpose.   To coin a phrase of Princess Giselle (Disney's "Enchanted"), "Wasn't that fun?"

The same kind of thing happens when threads turn nasty.  The strange thing is that even the nasty threads can be funny too.  They're not supposed to be, and I, personally, am sometimes reluctant to make public the fact that I've found one hilarious.  Still, nasty threads have that element of several different personalities adding comments that range from sarcastic to nice to bizarre.  It is, perhaps, the different directions and the potpourri of personalities that give someone reading the thread a little ride.   It's impossible to guess what may come next, and so often what does come next is something so "off-the-wall" or "out-of-the-blue" that the element of surprise probably contributes to the entertainment value.

It almost reminds me of the party game people play, in which one person whispers a message to the next; and by the time the message has been passed from one person to another several times it has become changed beyond any semblance of recognition.  Sometimes, too, once a thread has been kicked a little off-track,  some subsequent posters try to get in back in line; but it's to no avail.    In fact, it's almost as if once things have been "shifted to the side a little" the original purpose of the thread has been broken at least enough to prevent ever returning to it completely.  I guess the thing that always amazes and entertains me is where people come up with some of the stuff they come up with.    Because everyone is so different their comments are completely unique.    It's as if, once the original purpose of any thread has been abandoned, there is nothing cohesive about anything that follows.  The only thing that contributors have in common is that they're logged on to the forum.
This, of course, is exactly what administrators don't want happening on their forums; so it's with great guilt that I admit I find these bizarre strings of remarks as entertaining as I do.  (Sometimes I secretly wonder if I'll be banned just for thinking about how much fun these threads can be.)  Sure, some of the negative stuff is nasty and not the least bit funny.  Still (I can't help it), watching the creation of completely unique and spontaneous "thing" can be a lot more entertaining than a lot of other reading.  Most of the time these "things" contain a mix of just about every human behavior there is - aggression, sarcasm, friendship, support, teaming up, humor, attempts at peace-making, etc. etc.   It is "human nature on parade", complete with the good and bad aspects of it.

Trolls and spammers are, of course, especially disliked in forums; and it always amazes me how quickly people who are more Internet-savvy (I guess) than I come up with outside links and other information about suspected trolls and spammers.  Before you know it, the wild thread has moved beyond the forum and begins to involve e.mailing back and forth, checking out links, and other non-forum activity.    While, of course, I don't find some types of "mean-ness" at all funny, sometimes some of the meaningless attacks just are.  

After all, I was the quiet little girl in class who couldn't help but laugh at the wise-guy, class clowns.  They were so different from me.  I guess I admired them.   Even if I didn't admire everything about some of them, I couldn't help but see that a lot of their shenanigans were just plain funny.   Then again, I was also the little girl who, after school, enjoyed a good scream into the public library's mail slot, and enjoyed regularly teasing the "stuffy looking" people at the local newspaper office.   I don't know.  Maybe I'm just a little evil.   There's something about seeing a little disruption in an otherwise calm, polite, and well behaved environment.

On the forums, where there are so many people we feel as if we've come to know and like, it's just kind of humorous to see the occasional monkey-wrench tossed into the mix.   I don't want to see "hate speech" or cruel insults.   Those aren't funny.  Still, when a few people start essentially calling each other idiots and reverting to sixth-grade behavior; I can't help it - I find it entertaining.

It's always just a matter of time before people start talking about getting other people banned, or having threads deleted.   Sometimes that would be for the best.  Other times, however,  I kind of wish the most bizarre threads could be put together on one website.  They make for entertaining reading when one is tired of the more serious stuff in the world.

In one way, it is the rule-breaking nature of some threads that make them just a little more perversely (if mildly) thrilling.  There are people, I know, who don't find this stuff funny at all; and sometimes I don't either.  Still, in their weird way, bizarre threads have a way of showing an odd kind of "team effort" that, while not always a positive thing, can sometimes be at least a fascinating thing.   Sometimes, too, it is the bad behavior of forum posters that is actually a reflection of so many well intentioned hearts.  Sometimes what looks like bad behavior is really a matter of some people defending other people.  It can also be a reflection of the way a team will stick together when it seems necessary.   There are times when bad behavior is the result of people wanting to protect their otherwise peaceful forum environment.  Something interesting is that so often these out-of-control "bad-behavior fests" have a way of winding themselves down and letting peace and order be restored as a natural course of events.

As unruly and nasty as these threads can be, some out-of-control "bad-behavior fests" paint a picture of human nature at both its worst and best, and there's a part of me that kind of wishes some of the less than polite threads weren't quite so frowned on within the world of forum administration.  I know nobody wants to let forums be turned into outlets for nothing but inane or insulting remarks and angry venting, but once in a while one of these threads actually does bring a little life to a forum.  Yes, that "life", like all of life, includes the good, the bad, and the unpleasant; but it also includes that familiar "ROTFL" along with that steam that shoots out of people's heads.

Sometimes libraries really are too quiet, stodgy city newspaper offices really are too glum,  and things like forums can be so "cleaned up" and polite they can seem to be nothing but polite words politely entered by taking turns.  Sure, class clowns and troublemakers disrupt the class and the order of business,  and nobody wants shenanigans to be the order of the day every day.  Once in a while, though, there is something to be said for a observing a little human nature in action without editing, deleting, or otherwise intervening.  Sometimes if we look behind what seems to be bad behavior that goes on in a forum free-for-all, we will actually see glimpses of some pretty admirable behavior.  Between that, and enjoying the mix of different personalities and approaches to an unpleasant situation, I guess that explains my finding occasional bad behavior as entertaining as I do.