YDKS 

You Don't Know Shit

I got an F on my Math Exam. YDKS bitch!

YDKS by AspGod March 1, 2011

YDKS 

You don't know shit.

YDKS about pokemon.

YDKS by epic meal time shit talker February 22, 2011

YDKSAB 

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*

YDKSAB by Intentional Butt January 18, 2013