Incidental 37B is a fish who appears as a common background character in the series. He debuts in "Ripped Pants." He is frequently portrayed as a surfer, but he has also been a businessman, a normal homeowner, and a criminal. He is classified as a "hotdog" type incidental.
He is a purple fish with blue striped dark purple fins. His eyes are light yellow with black pupils. His most common outfit is a green baseball cap and a pair of yellow shorts with orange flowers on them. Sometimes, his shorts are light olive green with a dark orange flower design. In "My Pretty Seahorse," he is blue instead of purple and has a red hat. In older episodes, his eyes were closer together.
He is the last Bikini Bottomite to send a letter to Santa Claus. He writes his letter in Portuguese and remarks that he hopes Santa can read it. He later appears as a teenager with his father when all the Bikini Bottomites believe that Santa Claus was a fake.
He first appears as one of the Fancy! customers that SpongeBob steals a Krabby Patty from. He later appears when the scene is filled with customers after Mr. Krabs says, "...and you brought customers."
He sees SpongeBob and Squidward fused together and says "Rock on, freaky bro!" Later, at Squidward's concert, he says the same thing when SpongeBob reveals himself from under Squidward's cloak. This causes the crowd to cheer.