How to Tolerate People Who Talk Too Much
1 - Pretend you're asleep
The value of being able to feign unconsciousness if someone is talking your ear off should never be underestimated. Most (though, granted, not all) chronic over-talkers tend to stop when they think no one is listening to them. Pretending to be asleep is an easy way to ignore them without making them feel like you did it on purpose or having to explain why you're not listening: it speaks for itself.
If they try to wake you up, make a startled intake of breath and then apologize and say that you're just "so exhausted." Shortly afterwards, promptly fall back asleep, but make it gradual enough to be convincing. Falling back asleep is excusable and believable because you have already established the fact that you're exhausted.
2 - Talk over the person, and about something that doesn't interest them
Fight fire with fire. Be a chatterbox yourself and drown out anything they're saying with things that they don't know or care about, so they can't logically interject anything except "Uh-huh."
Completely reject any attempts of theirs to change the subject; change it right back.
In fact, be a little aggressive about it if they don't listen to you. Make unflinching eye contact and refuse to not be heard.
3 - Make an offensive or inappropriate joke that will breed an awkward silence
Hopefully that silence will last. Avoid all attempts by the chatterbox to make the situation comfortable again by saying something even more awkward or adding to the pre-existing awkwardness.
For example, if you know that the person who is talking too much is a feminist, make a chauvinistic joke.
Now, the joke will have to be extreme in its offensiveness, or it won't work. If it's a mid-level, slightly offensive joke or comment like, to go with our example, "Oh, women and their PMS," she'll just think you've been "brainwashed by society" into believing a stereotype about women, will give you the benefit of the doubt, and then proceed to talk your ear off about how what you said was wrong and offensive and not backed up by evidence, etc, etc, to infinity. In other words, you've made the situation worse by making what you said redeemable.
No, you need to make it clear by all accounts that you're too shameless to be forgiven or to be teachable.
For example, when it is a feminist we are encountering: "I think women subjected to ritualistic stoning deserve what they get."
You might get an initial "WHAT?" from your target (or any decent person, really), but afterwards it will just be awkward. Even if you append what you just said with "I'm just kidding. Har, har," a second later, it's too irredeemable. That's not even something to joke about, man.
Similarly, if the person you're dealing with has an embarrassing disease or has a close family member with some sort of embarrassing disease, make a joke about it.
Now, you might be thinking to yourself: But, that's so mean! I don't want to hurt someone's feelings or make them feel bad! To that, I say: Well...do you want them to shut up or not? Getting someone to shut up sometimes means you have to be an asshole.
4 - Feign an emergency
Once they start on one of their long-winded ramblings to nowhere, scream suddenly and grab a body part, pretending that it hurts. (Which body part is up to you, but I do not recommend certain ones that might give the wrong message, like your crotch.)
Be dramatic, but try to explain it as a temporary ailment, and not something that needs medical intervention. "Ohhhh! It's my trick knee again!" works just fine, as well as "Owww! Christ, something fell in my eye!" or even "OH MY GOD, a papercut! Anything but that!"
This can also be used as a springboard to change the subject--you can talk about how much it hurts and have a good excuse to not be listening to them.
5 - Tell them to shut up
Short and sweet. If you want to be mean in a direct sort of way, and assume they're the kind who would obey such a request (if not, you may need to resort to number 3), then give it a go.
It works best if you interrupt them during a sentence. Or, actually, it's just more emotionally fulfilling. For example:
"That reminds me of the time I was in Canada and--"
"--and I was going hiking...wait, what? Did you just say something?"
"Yeah. Shut up."
"I said I told you to shut up."
Good luck with this one.
No matter what method you try, remember that your peace and quiet are at stake. Stop at nothing!