Like a normal backslap, only harder, and thus more painful.
"By the time this loads I could Korean Backslap her 5 times!"
by Andy M August 18, 2003
When a korean guy is sodomisind another korean guy and just before he cums he takes out his cock and slaps it all over the other ones back.
"I gave Cho a korean backslap"
by Bum Dik Suk January 21, 2005