Sarcastically used to point out an unfunny joke. It originates from the act of slapping one's knee during vigorous laughter. Later took on a sarcastic meaning.
Comedian: I just flew in from Los Angeles, and boy are my arms tired!
Audience member in sarcastic tone: wow that's a real knee-slapper
Audience member in sarcastic tone: wow that's a real knee-slapper
by Joe February 12, 2003
Guy 1: So a guy walks into a bar...OUCH!
Guy 2: ROFL THAT'S A KNEE SLAPPER! *slaps knee*
Random Guy: Oh yeah? How bout a face slapper! *slaps Guy 1 and 2's face*
Guy 2: ROFL THAT'S A KNEE SLAPPER! *slaps knee*
Random Guy: Oh yeah? How bout a face slapper! *slaps Guy 1 and 2's face*
by Skullex May 18, 2008
A blunt that is so large, or otherwise so potent, a hit causes you to slap your knee and say "GAH'DAM."
by The Pizza Man March 30, 2006
From (Or inspired from) The Tom Green song "Pet names for Genitalia"
A penis.
Because it slaps your knees, if you're horribly unproportioned.
A penis.
Because it slaps your knees, if you're horribly unproportioned.
by Springloaded June 06, 2004
eg. danas brother sings and dances to 'its raining men' KNEE-SLAPPER
eg. claudias hair is ranga *slaps knee*
eg. claudias hair is ranga *slaps knee*
by dont you just wish you knew July 13, 2009
by KROGO June 26, 2005
AHAHAHAHA, that's a KNEE-SLAPPER!
by emelizabeth October 31, 2004