This is when a male, usually black (since they have the longest cocks), has a long enough cock and flexible enough body to have sex with himself.
The action is made by bending himself into a contorted form (often in a laying down position, with the legs over their head), with the penis tucked down and placed inside their anus.
In order to do this smoothly, the rectum is sometimes stimulated first with an erect object (i.e. finger/dildo/cucumber), to loosen the area and allow for insertion.
Omg, he's black! Why's he need me? He can just do autointercourse!