He has shiny black hair and dresses up in greaser-style clothing in that he wears a white shirt, red wristbands, blue jeans with a belt buckle like SpongeBob's, and black cowboy-like boots.
On his arms are blue-colored anchor tattoos. He also has very muscular arms for his small size. BlackJack has a very gruff voice and is circle-shaped, unlike SpongeBob's square shape.
However, when they meet each other as adults, he is only the size of the latter's big toe. As kids, BlackJack was much larger than SpongeBob.
