How to drink an unlimited amont of beer without getting drunk.
An infinitive number of mathematicians formed a queue at the bar. The first said "I have a pint of beer please." The barman poured it and put it on the bar. The second said "I'll have the same beer but only a half please." The third asked for a quarter of a pint. The fourth asked for an eigth of a pint, the next a sixteenth.......
At that moment the barman said "Stop!" He took a second glass and poured another full pint, putting it next to the first.
He said "The problem with you mathematicians is you don't know your limit!"
(very clever and true, btw)