Telling someone that you suck at something. Also used as a sexual reference to a blowjob (Oral sex).
1) "I'm joining the Basketball team" "Dude, Your Knees Are Red, you won't make it" 2)"Hey whose that pretty girl over there?" "Who? Kim? Her Knees Are Red from so many guys she's given head to."
by alex231 April 30, 2011