Butch Cassidy and the Sundance Kid is one of my all time favorites. There are so many good lines in that movie. Like the one Randy pointed out.
"Who are those guys ?"
"How can they do that. I can't do that. Can you do that ?"
"Can I move ?"
"Nobody's gonna rob us going' down the mountain."
No, we'll jump." "I can't swim." "The fall will probably kill us."