Knock the fuck out, a term used mainly when someone gets punched in the face, thereby resulting in a minor (or major) concussion or simply broken/bloody nose.
Nearly any sort of head-trauma, so long as it's very painful, is considered 'getting' knock the fuck out. You never use 'knock the fuck out' with an 'ed' at the end, because it ruins the point of the gangstuh-speak. Honestly, don't add the 'ed' or you get knock the fuck out.
Me: You better get me my weed by Monday.
John: Or what?
Me: OR YOU GET KNOCK THE FUCK OUT, THAT'S WHAT NIGGA!!
Me: Bitch you got my shit?
John: No, bitch.
Me: (Punches John in the face.)
Innocent bystander: Oh shit! You just got knock the fuck out!
A pedophile who's driving around looking for children so he can pull over and masturbate, and then leave.
Robby: Yo, dude. I just saw this guy and he was in this dark van.
Robby: He pulled over at the park, and he just sat in his car. It looked like he was jerking off.
Me: Oh! He was kiddy cruisin', eh?