This is an experimental thread. It is somewhat in the spirit of the Rationality Quotes Thread but without the requirements and with a focus on humorous value. You may post insightful jokes, nerd or math jokes or try out rationality jokes of your own invention.
ADDED: Apparently there has been an earlier Jokes Thread which was failry successful. Consider this another instance.
An infinite number of mathematicians walked into a bar. I'll have a beer, the first one said. I'll have half as much beer as the first mathematician said the second. I'll have half as much beer as the second mathematician said the third. The bartender looked at all of them, said you guys are jerks, and served them two beers.
A countably infinite number of mathematicians walk into a bar. The first mathematician orders a beer. The second orders half a beer. The third orders one third of a beer. The bartender says "whoa, I'm going to run out of beer!".