In the video game Call of Duty 5 there is a game type called NaziZombies, where wave after wave of nazizombies attack you. A zomb pet is created by shooting the legs of the last zombie in that wave and keeping it as a pet so people can get more ammo and stops the next wave of zombiesarriving because it is technically still alive.
Jack "O wait! Thats the last zombie in this wave, keep it as a Zombpet, while i get some ammo"
Sam "Alright no problem, I think I'll call this one Bubbles"