Blackjack's is the son of Sherm SquarePants. He is the klutzy and crazy half-brother is Stanley Squarepants.
Personality and Appearance
Blackjack was exactly the same size as SpongeBob until he went to jail and probably grew smaller cause of the lack of food and no excercise and shrunk to the size of SpongeBob's toe. Blackjack has a very gruffly voice and is circled shaped, compared to SpongeBob's square shape he also has very muscular arms for his small size. He dresses up in Biker-Gang clothing (white shirt, red wrist bands, blue jeans with belt buckle like SpongeBob's, and black cowboy-like boots). He has a pet worm, and lives in a cabin-like house only next door to his Uncle Blue SquarePants' house. Blackjack is known to be tough.
Relationship with SpongeBob
Cousin Blackjack is older than SpongeBob, and he used to be a bully to him. Blackjack also calls SpongeBob a "little man" not just because SpongeBob is younger than him, but due to the fact that SpongeBob used to not make any attempt to duel with him, and used to become scared stiff.
Relationship with Others
Blackjack is known to be a powerhouse. SpongeBob's parents were not scared of him at all. In fact, they find it fun that they play and chat together.
BlackJack went to prison for littering a lot.