Not much here. You do not need to apologize for it either.
Since, I like giving out advice, I'm going to here-
To be honest- your actions online should mimic your actions offline. There should not be two separate train of thoughts.
Yes, it is realized that you are on a computer talking to people from all around the world, however, your actions(talking/typing words) shouldn't be any different than if those same people were sitting in your living room/den or kitchen.
So, with that said- I can rather guess that when you left school today, the first thing you did was jump up and down, and yell once were outside. If not, then why do it here???
See what I mean? The most average person has no personal etiquette. Many do not even know what the word means(and I am not saying you do not).