Hoppy debuts in the fifth season episode "Hop Happy" (1964), where Barney and Betty Rubble acquire him as a new house pet. He babysits the kids as he takes them around in his pouch. Fred Flintstone regards Hoppy as an overgrown and obnoxious nuisance until the fateful day that the Flintstones and the Rubbles go out together on a picnic. The families' lives are endangered during the picnic and Hoppy goes for help.
Scriptwriter Warren Foster harks back to his days with the Warner Bros cartoon unit in the scene where Fred and Barney mistake Hoppy for a giant mouse. Hoppy appeared sporadically through the end of the series and is featured in various Flintstones merchandise. Most notably, he appears in The Flintstones: The Rescue of Dino & Hoppy video game for NES, made by Taito. A CG animated hopparoo makes a small appearance in the second live-action film The Flintstones in Viva Rock Vegas and while not meant to be Hoppy it was a clear reference to the character.