I have 2 movie fav scenes and one favrite scene from a tv show.
First is from the movie The Hangover, where the naked asain dude pops outta the trunk and starts wailing on the dude with a crowbar, i was rotflmao for a good five min at the theatre.... never roll on the floor in a theatre, it does not go well.

Second is from the movie dead alive (braindead in europe) where father McGruger fights the zombies : http://www.youtube.com/watch?v=C_Q5UuN_l88 (warning for this one, it contains one bit of foul languge and a needle up a zombies nose)

And from the TV show Buffy the Vampire Slayer, where willow, xander, amy and anya walk into a cafe and find Giles singing : http://www.youtube.com/watch?v=DI0LcKSZapw