Knock Someone's Block Off Meaning

(idiomatic) To strike a person in the head, causing him to fall to the ground, especially in an unconscious condition; to beat up a person.

Example: 1895 Feb. 12, "Ring Gossip," Providence News (USA), p. 6 (retrieved 6 July 2011):
  "I can't stand the sight of him," he would say, "and I'd be glad if somebody would come along and knock his block off—when he was not in the ring."
1941 June 23, "People," Time:
  An airport cab starter threatened to knock Fiorello H. LaGuardia's block off when the New York Mayor parked his car across the taxi line.
1957 Jan. 25, "Guard Chief Irked," Rock Hill Herald (USA), p. 4 (retrieved 6 July 2011):
  "If anyone wants to call a guardsman a draft dodger, tell him to stand in front of me and say it and I'll knock his block off," Gen. Fluck said.
2008 Feb. 23, James Barron, "Man Departs a Life Lived on the Fringes of Fame ," New York Times (retrieved 6 July 2011):
  Mr. Gottfried said Miller announced, “I'm going to knock your block off”— and punched Mr. Jones, who was thrown against a buffet table.