A person who surpasses all conventional boundaries of prudence, intuition, common sense or intelligence. Can be used to describe someone given a single, isolated instance or used as a general assessment of one's intellectual or intuitive competency.
A: Hey man, I'm not feeling so well. My mother just passed away and I just spent two-thirds of my life savings on her funeral. I'm starving and I'm about to be evicted from my apartment. My wife just left me as well.
B: Shit son, sorry to hear that... Hey, you think I can get that 20 bucks I lent you 5 years ago?
A: Man, shut the fuck up you dumbass nigga.
C: Dumbass nigga...
D: Yeah, shut the FUCK up you dumbass nigga.
B: Aite, aite....