knock someone's block 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
Farlex Dictionary of Idioms.

knock someone's block off

Beat up someone, as in If he doesn't leave at once, I'll knock his block off. This hyperbolic term employs block in the sense of "head," a usage dating from the 1600s. The idiom, however, dates only from about 1900. Also see beat the living daylights out of.
See also: block, knock, off
The American Heritage® Dictionary of Idioms by Christine Ammer.

knock someone's block off

hit someone very hard in anger. informal
Block is used here in its informal sense of ‘head’.
See also: block, knock, off
Farlex Partner Idioms Dictionary
See also:
  • knock (one's) block off
  • knock block off
  • I'll knock your block/head off!
  • block
  • knock someone’s block off
  • cut off at the pass, to
  • the block is hot
  • What will that prove?
  • go on the block
  • block off
References in periodicals archive
I don't want to knock someone's block off. How do you throw it?'
Cold Feet Down Under Tie Me Kangaroo Down, Sport... and other Aussie challenges; When the Cold Feet gang hit Sydney's lush Balmoral beach to film the final episode of the current series, we didn't want them lounging around in the sun. Oh no, siree. So we posed them some tricky-dicky tasks. Were they fair dinkum or big Sheilas when it came to the crunch?