Oliver Bartholemew "Shank" Jackson, an ex-convict, was the big brother of Charmaine, a girlfriend of Marlon's in the episode titled "I Do". The part of Shank is played by comedian/actor Bernie Mac.
About Charmaine
Charmaine, who is the apple of her overprotective older brother Shank's eye, introduces Shawn and Marlon to him; he impresses Marlon when Shank gives him a $100 bill to take his sister "out on the town". Soon, however, he reveals his true colors when he tries to strong arm Shawn into doing business with him (he wanted 20% of all profits and receipts) as well as Pops (he also wanted 15% from the diner). He recants only when confronted by Marlon, but only to, after Shawn admits that he and Charmaine did get intimate, demand that Shawn marry her; Charmaine, who wasn't hot on the marriage idea like Shawn, gets Shank to leave the Williamses alone by confronting him, and embarasses him by revealing his real name, and that he still wets the bed, and threatens to tell their mother who suffers from high blood pressure, about him carrying a knife!