Correlation
Permanent link to this comic: http://xkcd.com/552/
Image URL (for hotlinking/embedding): http://imgs.xkcd.com/comics/correlation.png
[[A man is talking to a woman]]
Man: I used to think correlation implied causation.
Man: Then I took a statistics class. Now I don't.
Woman: Sounds like the class helped.
Man: Well, maybe.
{{Title text: Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'.}}