A phrase commonly used on several occasions. It's almost always said together with at least two people. It usually expresses excitement, and can also be said after you've burned someone. It's used a lot in Regular Show.
Guy 1: Hey man did you hear, they're giving out free pizzas!
Guy 2: With cheese filled crust?
Guy 1: You know it!
Guy 1: (insulting) You'll never be the man your mom is!