look up any word, like cunt:
-An expression said aloud to someone to let them know you know already.

-Used in a sarcastic tone of voice, often rolling your eyes upward gets the point across better. It can be a bit insulting too.

-Its like saying "why did you waste your time telling me that" gesture.
Easy example:

person1: "Red and Blue make Purple"
person2: "No Da! I know that!"
by ki January 31, 2004