Definition
To be brave; to show some courage, especially in a situation in which one has so far failed to do so.
Origins
Clipping of grow a pair of balls.
Also Said As
See Also
How People Actually Use It
Telling someone they don't have the balls that they SHOULD have to do something "manly" Usually a conversation between 2 or more guys.
"Jake: I really like Mikayla, but I don't think she would go out with me... John: Stop being a pussy, grow a pair and ask her out!"
Source: Urban Dictionary