The Boat Jacker is a huge, slender, dark lavender muscular fish that wears a ski mask, a torn up dark blue jean jacket, and dark blue pants. He carries a crowbar.
He stole SpongeBobs car and went to the bar, SpongeBob later successfully stole it back.
There is another Boat Jacker mentioned in "No Free Rides," when SpongeBob thought Mrs. Puff was one of them. It is possible that this Boat Jacker may be related to the reference SpongeBob made at Mrs. Puff.
The Jacker was in The SpongeBob SquarePants Movie video game, only smaller, and in the levels Thug Tug and Dennis Strikes Back. The Jacker in the game, however, has a different voice, he grunts which are higher pitched than in the real movie.