Old MacDonald Timmy gets me every time.
“ Timmy Burch first appears in “The Tooth Fairy Tats 2000”; his three scenes in the episode having little relevance to the central plot. Comedy Central originally wanted to remove him from the episode, in fear of potential controversy over the inclusion of a mentally handicapped character.[5] Series creators Matt Stone and Trey Parker pushed to keep the character in the story, with their basis being that although Timmy is different, the other children in the series treat him equally.”