Avocado is one of the four major characters from the in-universe parody series Cow Duck Avocado Mantis. He is intended to be an alternate version of Banana.
Like Banana, Avocado is quite lazy. Since Banana took over his role in the series unauthorized (which led to his firing), Avocado became very hostile towards him and punched him in the face as an autograph.
Avocado is the least similar looking to any of the actual Pig Goat Banana Cricket quartet. He initially is the seed of an avocado and wears an avocado suit to cover it during performances.