In the couch gag for the episode "The Cad and the Hat", Homer traveled to different TV shows to find the stolen painting of a sailboat. One of the shows he visited was South Park where the four main boys awaited him and cussed him out with everything they said being censored. As Homer ran back, he trampled the entire South Park cast and killed Kenny.
In The Cad and the Hat, Ralph Wiggum dresses as Kenny and is hit by the school bus, causing Otto to yell in shock that he killed Kenny, only to correct himself and remember that he killed Kenny yesterday.
Kenny's appearance in The Simpsons is different than how he's depicted in South Park. In South Park, he normally wears an orange parka and brown gloves, but in The Simpsons, his paper-like style is more exaggerated and he wears a purple hat that covers his ears with an orange puff ball on it. He also has a purple jacket, an orange scarf that's wrapped around his mouth, light lavender gloves and pants, and black shoes.