xkcd is always good, but I hadn't seen this particular one until today: http://xkcd.com/149/

It has the merit of being either hilarious or utterly incomprehensible. Well, I think that's a merit. Probably.

Incidentally, if you're not familiar with xkcd the title text (mouseover tooltip thingy) for each comic contains an additional comment or joke. I hadn't noticed this until my friend Ian drew my attention to it, so now I have to go back and read them all again. Hurrah!