I'll knock your block/head off!

knock (one's) block off

To strike someone with great force, usually in the head. If you insult me like that again, I'll knock your block off!
See also: block, knock, off

knock (one's) head off

To strike one with great force, usually in the head. Usually used as a threat or a hypothetical action. If you insult me like that again, I'll knock your head off! That football nearly knocked my head off. I'm glad I ducked in time!
See also: head, knock, off

I’ll knock your ˈblock/ˈhead off!

(British English, spoken) used to threaten somebody that you will hit them
See also: block, head, knock