Back at the Barnyard (2007)

Season 1: Episode 25

After Snotty Boy returns to torment the animals, Otis accidentally falls on him and becomes unconscious. Luckily, he's got a pulse and they decide to take him back to the Beady's, but Abby says that Mrs. Beady will blame them. Otis sends a disguised Pig over to the Beadys' as Snotty Boy so they don't get suspicious. But Pig enjoys being Snotty Boy so much that he decides to stay as him forever. Meanwhile, Snotty Boy gets amnesia and the animals realize that the only way to get Pig back is to turn Snotty Boy back to his old mean, obnoxious jerky self so Mrs. Beady will recognize him and because Snotty Boy is annoying them with his newly found kindness and sweetness.