Hm.... Monty Python's Life of Brian was pretty funny.
I also like Kyle Cease, he's rather funny really. As is Christopher Titus.
Spaceballs and History of the World part 1 where also really funny movies.
But probably my favorite thing is The Whitest Kids U' Know. This one in particular
<youtube=SIHHi790ldE>
I should warn you, there's some rather adult material in that.
Other rather fun vids are:
<youtube=ct2AWh-nKSk&feature=related>
<youtube=Fqq051BU2MY&feature=related>
<youtube=IRcMVMeXPQ4&feature=related> (side note, I told you so LotR fans, that book could have been cut down to ten pages if Gandalf actually just did this)
<youtube=aY-nGm4DxSU>
Warning some most of their stuff isnt exactly young children aged appropriate.
EDIT: *sigh* the Spoiler isnt working for me, so oh well, guess we'l just have to deal with this.