A way one can dismiss concerns and/or animosity others have towards them. Can refer to practically anything, but usually is reserved for illicit or illegal things.
Moneesha: "I'ma have sex with whoeva I want! It don' even matta!"
Tyra & Monique, Moneesha's Friends: "You need to stop Moneesha! You're going to end up dead or with a disease. We're really worried about you."
Moneesha: *waiving hands and pointing fingers* "Whateva! Whateva! Y'all don' know me! Y'all don' know me!"
"And when you're in that thaying, she makes the homies sing, ba-dum-bway, ba-dum-bway, ba-dum-bway. Y'all don't hear me though. Ain't nothin wrong with being a Trojan man, when you're riding..."
It's like Doctor Who, but for really smart people. Plus, it will extend your brain to the point where you'll become the universe
Person 1: Do you watch Doctor Who? I love that show!
Person 2: Nah m8, that show is for dumbasses like you. I watch Doctor Whomst'd've's'nd't'y'all, and that is THE SHIT!
Person 1: What the fuck