it can mean one of the following:
1. To ball. As in to actually play basketball
2. An adjective. Its impossible for guys to think of anything beyond the point of "good, bad, and ballin"
2. Dude, that is so ballin.
2. possessing exemplary athletic ability, especially in the sport of basketball.
2. Wow, Michael Jordan was ballin' before he shot himself in all of his joints.
2.) Making money
The source of 1. is obvious; 2. come from selling rock or crack cocaine. You start making good money when your dealing with balls (8-ball) and up, which is a half a quarter ounce, or 3.5 grams. A half a b (1.75 grams) is the lowest on this scale and what low end dealers might grab. On the street a half a b goes for $100-$125, which you can convert to about $170. The turnover is not extremely high, but the rate you sell it at is as you can easily turnover that amount in 20 minutes or less. The more balls you deal with, or sell, the higher the turnover.