The Mayo Monster is a creature that forms in the Radiant Realm after Ali-A drags CODY 2016 out of a mayonnaise pit, which had actually just been the Mayo Monster's dormant state. Before the Mayo Monster can attack Ali-A or CODY 2016, though, it is challenged by Gremmie, who is ultimately able to mount the beast and ride it through a wall of the tower, which causes the entire structure to fall over. However, CODY 2016 notices CODY 2017 in the top window and smacks him hard enough that the tower falls the other way, killing Gremmie and squishing the Mayo Monster, but not killing it. The Mayo Monster is later able to capture CODY 2018 temporarily, due to it not being compatible with CODY 2018's ability to move through anything that matches his colors. After CODY 2018 eventually escapes from the Mayo Monster's hold, the Mayo Monster is never seen again.