An infinite number of mathematicians walk into a bar. The first mathematician says to the bartender, “I’d like a beer, please.” The second mathematician says, “I would like a half a beer, please, sir.” The third mathematician, smiling, says, “I’d like half of a half of a beer, please, good sir!” The bartender, glancing down the line, says, “You’re all morons!”, pours two beers and walks away.

*(If you don’t get it, check the tags. If you still don’t get it, well, try Wikipedia.)*