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
something that is stupid and funny at the same time
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*
adverb. A term used to describe a dumb-ass joke. Its inception was the result of someone noticing their friend slapping their thigh/knee when a joke was told. It's an official "knee slapper" when the person laughing sqints their eyes, slaps their knee, and can barely speak due the amount of laughimg taking place. This definition is considered a "knee slapper".
What do you call someone who doesn't fart in public?
A private tutor!!
Sumthing very funny and ridiculous
Thats Wat She SAid
ROFL THATS A KNEE SLAPPER!!!
When someones penis is so big that it slaps the inside of their knees when they walk.
What size condom would you like?
Let's just say it's a knee slapper.
A blunt that is so large, or otherwise so potent, a hit causes you to slap your knee and say "GAH'DAM."
We's burnin knee slappers in this bitch.
1) An otherwise unfunny, awkward, or just stupid joke. Usually a dad pun or something of the sort. Said after this to show that it should have never been said in the first place. Invented by hillbillies and rednecks when sitting on their porches, slapping their knees when somthing funny happens.
2)said after something funny and stupid happens.
dumb guy:"Two peanuts are walking down the street, and one of them was assaulted!"
normal guy (slaps knee and fake-laughs):"Wow! That sure was a knee slapper!"
guy skates and falls off rail, hurting his knee and friend laughs.
Later they are talking and laughing about a dumb joke.
friend:"wow that sure was a knee slapper!" (slaps knee)
guy:"yea!"(slaps knee very hard, and dislocates it from the earlier accident)
friend:"no that's a knee slapper!"