At "TOP 100 funniest one-liners on the internet" you will find a list of jokes that suits the 140 character limitation on micro blogging services such as Twitter. To give you an example:
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If I agreed with you we'd both be wrong.
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That's what she said!
http://instantrimshot.com/
One or two are from Broadway shows.
It always disappoints me when people think history started in 1994
Wait, you mean there was stuff before 1994? Then how come I don't remember any of it? And don't give me that, "Because you're only 20, you idiot!" stuff my mom always gives me. I'm tired of hearing it.
(Just kidding. It bugs me, too. Learn history, people!)