A black girls BooBies which are most often than not bigger than white girls BooBies.
But the word is more than often shouted than said, because you are proud of it. (an example which will make sense will be below)
It can also be said for practically anything, for example, instead of saying "word", "no way" or "really" you could slip that word in there but the trick is to keep a straight face. (after a while, it gets more and more funny)
.......as seen on tv
Scott: "Hey Nathan, what you gunna do today?"
Nathan: "Im gunna get my self some NIGGA TITTIES"
Nathan: " NIGGA TITTIES"
*and then he acts to as if he was moterboating the niggatitties, and then acts as if he has a niggatittie in his hand and hes licking the nigganip*
James: "Where were you last night George?"
George: "Guess what, i got laid"
James: "SHUT THE NIGGATITTIES UP" :O