The Fonics Monkey is the key component of a boxed set called "Hooked on Monkey Fonics". The set is designed to help children learn to spell (particularly focusing on phonics) and includes the monkey along with a miniature drum set and a tape. The idea behind the set is for the monkey to keep the beat whilst the tape narrates instructions; the tape mentions how a replacement monkey can be ordered if the one included in the box is dead.
Liane Cartman bought the set to help Eric Cartman win a spelling bee. After a successful first attempt at learning with Fonics Monkey, Cartman becomes over-confident in his abilities as a speller and takes the monkey with him to the spelling bee. However, when he is ask to spell the word 'chair' (the same word Phonics Monkey helped Cartman successfully learn earlier in the episode), Cartman looks expectantly at the monkey who chooses to masturbate instead of helping Cartman. Cartman loses, and Fonics Monkey ends up loafing around the house with Cartman when he begins 'home schooling'. Phonics Monkey later kills Kenny in the episode. This is an instance where when Kenny dies and Kyle does not say "You bastard!" Instead, after Stan says "Phonics Monkey killed Kenny!" Cartman responds, "You damn straight he did." At the end of the episode, Fonics Monkey can be seen playing his drum-set with the band Dio to the song "Holy Diver" at the school dance. What happened to Phonics monkey is unknown, although perhaps he joined the band Dio to play drums for them.