1) The way in which a 'gangster' sits in the driving seat of his 'ride'. ie, leaning towards the
passenger seat, with one arm resting on the glove/tape box
in the middle, the other hand on top of
the wheel and head ducked low under the rearview.
2) A type of walk or bowl employed by a 'gangster' that makes it look like said gangster has a slight limp from prehaps having a 'cap' 'popped' in their leg.
Thus leaning to the opposite side and taking the weight of the injured leg produces a gangster lean. An injured leg however is by no means a prerequisite for having a gangster lean, many addopt the style in an effor to look 'hard' or 'cool'