In Midnight Cowboy, Dustin Hoffman's character (Ratso Rizzo) says:
"You can't scratch yourself without getting a bellybutton up the old kazoo there."
This was when he was talking about going to Florida, Miami Beach, and the ladies there. He was talking to a handsome man (Jon Voight), who was trying to be a hustler in New York but could not succeed.
Clearly I don't know the meaning of scratching or bellybutton, or how they can be related to each other, or I cannot find the logic by which to understand this sentence using my current knowledge of English.