He has olive green skin and a dark olive green-striped dorsal fin. He also has three dark green spots on his head and wears a black mask. He has scales on his back and has black and white stripes on his clothing, as typical prisoners wear. Many other similar criminals have made cameo appearances all throughout the series.
When SpongeBob and Bubble Buddy go to the Krusty Krab, Squidward complains that Bubble Buddy can't eat at the Krusty Krab, and that his money is no good there. Mr. Krabs appears out of the cash register and says that everyone's money is good. The scene then shows the criminal with a big bag of cash on the table, implying that stolen money is good money for the Krusty Krab.
A related character who was also a criminal appeared in the episode "Truth or Square."