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 a purple fish. His fins and dorsal fin are dark purple with faded blue stripes. 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.
"Chocolate with Nuts"
He appears when SpongeBob and Patrick knock on his door to sell chocolate. Patrick starts at him creepily, causing him to slam the door on Patrick's eyes.
He appears at the Snail-Po Headquarters. He is pointing at an image of the Snail-Po can design.
"Le Big Switch"
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.