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Similar to the 1st Round Knockout, however, this phenomenon occurs late at night instead of early in the morning.

This move is generally used to humiliate those who fall asleep too early. (i.e. your girlfriend, boyfriend or uninvited guest at a party).
"I waited all damn day for a romantic night and the bitch fell asleep as soon as she got home. I gave her a 12th Round Knockout, took a cold shower, and went to sleep.
I got up early this morning to wake her with an alarm cock."

"Bucky gave Keith a 12th Round Knockout for eating all the spaghetti and falling asleep during the UFC fight!"
by Wildman Bill March 05, 2010
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