knuckle sandwich
US /ˈnʌk.əl ˌsænd.wɪtʃ/
UK /ˈnʌk.əl ˌsænd.wɪtʃ/

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.
a punch in the mouth