Knock it off!
Definition 1 of 1
Pro Tip 1/3Informal Setting
Use 'knock it off' in casual situations among friends or family. 
Guys, knock it off! We'll miss the movie.
Pro Tip 2/3Not for Authority
Avoid using 'knock it off' with superiors or formal contacts; it's too casual. 
N/A
Pro Tip 3/3Frustration Expression
It conveys irritation or annoyance. Say it when you're losing patience. 
If you don't knock it off, I'm leaving.