3 championship rings - Kobe is referring to the 3 NBA championships that he has won (players receive a ring for each championship)
'cause- short form of the word "because"
be hungry- in this context "be hungry" means to want something a lot
'bout- short form of "about"
stomach growling- the noise your stomach makes when you are very hungry
oh snap- colloquial phrase for "oh wow", or "oh!" (implying surprise)
what's up- a colloquial expression meaning "what is going on?" or "what is happening?"
'em- short form of "them"
hide and seek- a game where one person hides, and the other person searches for the person hiding