Pet Threat is the first half of the 2nd episode of Dave the Barbarian.
Faffy is sad because the family forgot to get him anything during Dragon Appreciation Week, so Dave buys Faffy a diseased weasel for a pet. The diseased weasel gets all of Dave's attention, but Faffy tried to tell everyone that he is evil but nobody believes that they yelled at him. so Faffy runs away. The weasel turns out to be Chuckles the Silly Piggy, who wants to steal a magical fruit hidden in Faffy's room.