The series is about a family of hippos that live in a safari park in Africa. They just laze around during the day, but once it reaches closing time and the visitors leave the park, the Happo family begins the real fun. Members of the family include Astro Happo, who wants to travel to the Moon at all costs, Stunt Happo, who draws attention to himself with his accident-prone stunts, and Party Happo, who is there to party.