look up any word, like dirty sanchez:
 
1.
Where you put your knees inside your shirt and on webcam gives the appearance of giant boobs.
I saw an emo chick on chatroulette with huge tits. It was actually an emo dude with kneeboobs
by RunJun February 09, 2011
 
2.
A women with very saggy boobs. As if they are approaching the knees.
Sick! That girl has kneeboobs!
Or if that's your type.
Awsome, that chicks got kneeboobs!
by foomanlinux June 21, 2006