Fear and Loathing in Los Vegas, even though I'm not totally sure it's a straight up comedy or that I morally should be laughing at the events of the movie. Two guys who are out of control on drugs the entire flick, who freak other people (and each other) out, dodge bills and ruin hotel rooms. ...actually, that's pretty funny. With lines like:
SPOILER!!:
Raoul Duke: There's a uh, big machine in the sky, some kind of, I dunno, electric snake, coming straight at us.
Dr. Gonzo: Shoot it.
Raoul Duke: Not yet, I want to study its habits.
And:
Dr. Gonzo: [spills the cocaine] Jesus! You see what God just did to us, man?
Raoul Duke: God didn't do that, you did it. You're a ****ing narcotics agent, I knew it! That was our cocaine, you ****ing pig swine whore...
or:
Raoul Duke: I'm a relatively respectable citizen. Multiple felon perhaps, but certainly not dangerous.

Reading some of the lines on the IMDB page made me lol all over again. Other than that... um... I really liked Pineapple Express, Hot Fuzz, Monty Python and the Holy Grail, and Fantastic Mr. Fox for the comedy? Most comedies lose their funny on repeated watchings, though. A lot of 80's comedies like Ghost Busters, Blues Brothers, and Back to the Future I love because they're just awesome movies, straight up.

As for tv shows, Arrested Development, The Venture Bros., and old seasons of the Simpsons regularly caused me to lol. Anyhoo...

Wuv, Yer Mom