Abbreviation for: You Don't Know Shit About Boxing
Shortened version of the phrase coined by esteemed boxing trainer Roger Mayweather who used to it describe the lack of real boxing knowledge possessed by boxing journalists and fans.
Pactard : Marquez is a cheater, he is on PEDS!
Sane Person: YDKSAB, Manny got KTFO because he lunged in and got caught.
Pactard : Your a flomo, Floyd is a chicken.
Sane Person: *facepalm*