Chum Chum is Fanboy's best friend and sidekick. Although he is younger than the other main characters, he is still in the same class as them. Show creator Eric Robles explained on the Nickelodeon message board that this is because Fanboy snuck him into his class and the teacher never noticed the age difference. Chum Chum is extremely energetic and high-spirited, and possesses an indomitable enthusiasm and childlike jocularity. Chum Chum has brown hair, wears a black eye mask and gloves, an orange and yellow uniform with his logo on the chest, a yellow cape, black high-top sneakers, and his underwear on the outside of his costume. In the pilot from Random! Cartoons, Chum Chum wears an orange collared shirt with yellow buttons on the chest instead of his logo. Chum Chum seems to be incapable of achieving more than 3 points on Boog's "Chimp Chomp" video game, although Chum Chum is ecstatic even when he loses.
Chum Chum appears as a playable character in Nicktoons MLB. He throws left-handed.
- Screw: ****
- Slider: ***
- Curveball: ****
- Changeup: *****