Beer joke for an infinite number of mathematicians - Zeno's paradox revisited.

An infinite number of mathematicians walk into a bar. 

The first asks the bartender for a beer. 

The second asks for half a beer. The third one says he wants a fourth of a beer. 

The bartender interrupts, puts two beers on the bar and says:
 “You guys need to learn your limits.”

Zeno's four paradoxes.
The joke's been around for a few years.

A beer science joke but not as good:    "A solar physicist walks into a bar, gets the bartender's attention, and says "I'd like a Mexican beer, please." The bartender immediately begins shouting "OK, everybody out! Right now! Everyone out of the bar!" and rushes the patrons into the street. "Darn," says the solar physicist, "I should have seen that Corona Mass Ejection coming!"

Better is this one (with more at the link):
"The bartender says 'We don't serve time travellers here'.
A time traveller walks into a bar.

One more with an infinite regression:  (Commenter kenwdoelq at Wattsupwiththat).

An engineer and a mathematician are competing for a beautiful woman. The engineer and the mathematician are told, “You can go to her, but you must travel this way; go half the distance, and then stop; then go half the remaining distance and stop; go half the remaining distance, and then stop, and so on.”  The mathematician never starts, because he knows he can never reach her. But the engineer takes off running, because he knows that he can get close enough for practical purposes.