Since most of mine have already been posted, here are a few others:
"Because we were inverted." Top Gun (probably gets quoted too often but is a well known quote).
"I'm your Huckleberry." Tombstone
"The hardest part about this is the cleanup afterwards." Kung Fu Panda
Not really a movie, but some RPG's tend to be movie like so here goes "The algorithms I have been programmed with do not support the comprehension of illogical human thought." KOS-MOS in Xenosaga: Der Wille zur Macht.