Mathematicians hunt lions by going to Africa, throwing out everything that is not a lion, and catching one of whatever is left. Professors of mathematics prove the existence of at least one lion and leave the capture of an actual lion as an exercise for one of their graduate students.
(Bjørn's maths blog)
Pointed out to me by rosefox. The post actually is quite long with some quite esoteric maths in there. If you laugh AND make it all the way through the post, you're a dweeb. :)