FBI Technician: What's forget about it?
Donnie Brasco: Forget about it is like if you agree with someone, you know, like Raquel Welch is one great piece of ass, forget about it. But then, if you disagree, like A Lincoln is better than a Cadillac? Forget about it! you know? But then, it's also like if something's the greatest thing in the world, like mingia those peppers, forget about it. But it's also like saying Go to hell! too. Like, you know, like "Hey Paulie, you got a one inch pecker?" and Paulie says "Forget about it!" Sometimes it just means forget about it
http://www.youtube.com/watch?v=pS6zJ7IsJkM