Flippin' birds is not selling drugs in general like said above, that is completely wrong. A bird is a kilo of cocaine marked with a stamp of a bird showing where it came from.
Lets head to Miami, pick up a bird and roll dat bitch to tha H-Town to flip it. Lets flip birds
To hussle by sellin' drugs (slangin').
Those niggas be husslin'...they be on the corner flippin' birds.