Smitdaddy took my favorite. How about -
Marge - Homer, we need to get you to a scientist.
Homer - Is it Batman??
Marge - No Homer, its not Batman.
Homer - Batman's a scientist.
or
Moe - Hey Apu, you got a breakfast cereal for people with syphillis?
or
Lenny - Alchohol and night swimming, its a winning combonation!
or my all time favorite -
Mr. Burns - Dogs are idiots.
Speaking of Burns, anyone else like the one where the Burns casino is built? Theres a part where Burns remembers when he was a kid and he cripples and old Irish man with his bumper car. Then it shows him laughing for the next week straight, while hes at work, in the shower, eating, etc. I almost shit my pants when I first saw that one.