infinite mathematicians enter a bar. the first orders a pint of beer, the second orders half a pint. the third orders a quarter pint, and the bartender cuts them off there and just pours them two pints

after a time the mathematicians indicate they're ready for another round. as before, the first one orders a pint and the second orders a half. when the third orders a third of a pint the bartender says "actually i think you've all had enough for tonight"