1. In L.A. gang culture slang, a wannabe.
2. In sports, an athlete who excelled as an amateur(high school, college, etc.), but when they turned professional, failed to live up to the expectations.
> 1. "Your own barrio doesn't back you up, they just look at your ass and call you a poo butt."
> - Kid Frost, "La Raza"
> 2. Adam was the bomb in college, but when he went to the NBA, he got straight dominated. What a poo butt.