In episode 99b when the Keroro platoon build an aquarium, they don Dolphin costumes to form the Keroppas group and star in the aquariums' main (and only) attraction; the Keroppas water circus. The show is basically the five of them performing dolphins tricks while in costume namely jumping on comand, going up on their tail fins, ball balancing and jumping through a flaming hoop (a trich which Keroro ultimately fails at, instead catching on fire for a moment)