Straighten your face!

This saying is reserved for convicts, and hardly ever used on the streets(except by ex-convicts). A convict will say this when he is ready to beat the brakes off a man, or someone has disrespected or just put himself in harm's way by not paying attention. Knuckle up, it's on.

What's up bruh? You asking questions about one of my soldiers, you must done flipped your lid. What's up straighten your face!, partner