[AndyShields]

I think Mean Girls is popular because despite being a teen comedy it isn't written by a bunch of kiddies who think genital jokes are like totally hilarious!
Oh and it has a bunch of witty one liners that can be used as jokes I guess.
The best one blatantly being the Brutus/Caesar bit.

(Oh and Lacey Chabert's hot! That's blatantly the real reason)