I thought there was a thread for comedy movies but I didn't see one. I just recently watched two newer ones and they both cracked me up. Hot Rod and Hot Fuzz.
If you like SNL or Family Guy you will like Hot Rod, there's a bunch of stupid laughs in it and I couldn't get enough of them.
Hot Fuzz is a british comedy made/played by the same people that created Shaun of the Dead.
I loved both of them, they're not my favorites or anything but I got a kick out of them.