Not exactly the best one-liner by a long-shot, but the first one that comes to mind-- in Little Mermaid, King Triton asks Flounder if he knows who Ariel's mooning over, and Flounder goes, "Don't ask me! I didn't even know it was love until the second chorus!" (They'd just finished a song called "She's In Love," and Flounder came in on the second verse.)
Also, I liked in The Lion King when the "I Just Can't Wait To Be King" started and the strange-looking rainbow curtain came down-- Zazu said, "What? This wasn't in the cartoon!" And then he added, "Looks like a shower curtain from Wal-Mart."
I guess I just love it when the script breaks the fourth wall.
In my pants, she has burst like the music of angels, the light of the sun! --Marius Pantsmercy