Fred Flintstone's pet

DINO

["Think about the animated prehistoric family sitting in their living room; what's wagging its tail?"]

The clue "Fred Flintstone's pet" leads to the answer "DINO" through a direct cultural reference. In the popular animated television series "The Flintstones," Fred Flintstone is the main character, and his pet is a small dinosaur named Dino. This connection relies on familiarity with the show and its characters, making it straightforward for those who know the series.