1 definition by Fat Boy Canada

to incapacitate or render oneself unconscious by means of physical, or mental, abuse or deprivation to one's own body.
"You are ridiculous. Knock yourself out now!"
"There is no way I can win this race. I might as well knock myself out!"
"I was about to kick that guy's ass for the way he was talking to my girlfriend, but he knocked himself out already."
by Fat Boy Canada October 8, 2009
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