Fanboy and Chum Chum
Chum Chum is Fanboy's best friend. He is younger than the characters, despite being younger, he's in the same class as them and the show's 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 wears an orange and yellow uniform with white briefs worn outside his costume.