Something so hilarious it makes u slap your knees. Funny moments that cause uncontrollable laughter.
My niece and I seen a man with a car dealership flag on his bicycle chased by a bunch of Chihuahuas, it was such a knee-slapper!! Hahahaha
by MainRain October 13, 2018

Street fighter Alpha Dalton von Staffenburg- I was there when the ticking time bomb went off, I saw the blast, I saw his knees get smashed, I saw him drop like a stone. Paulie Mussolini is dead.
Paulie Mussolini- Other than a few scrapes, bruises, and marks, I am unhurt, I was never in danger. I will not give up my happy Jew hunting.
Paulie Mussolini- Other than a few scrapes, bruises, and marks, I am unhurt, I was never in danger. I will not give up my happy Jew hunting.
by Solid Mantis April 28, 2021

by Jerry Smith's Dog November 14, 2021

by hklr May 10, 2016

A saying a person does when another person says an unfunny joke but you're being sarcastic about it, indicating it was the funniest joke you have ever heard in your life. (being sarcastic if you didn't get that)
"Hey Billy, why did the chicken cross the road?... TO GET TO THE OTHER SIDE!" *laughs hysterically*
"What a knee slapper, Timmy!" *slaps knee*
"What a knee slapper, Timmy!" *slaps knee*
by lovelyleftorgan777 May 4, 2022

by pcvbg26 August 29, 2011

by big dookie December 31, 2007
