knuckle sandwich

US /ˈnʌk.əl ˌsænd.wɪtʃ/
UK /ˈnʌk.əl ˌsænd.wɪtʃ/
"knuckle sandwich" picture
1.

a punch in the mouth

:
If you don't stop talking, you're going to get a knuckle sandwich.
He threatened to give me a knuckle sandwich if I didn't leave.