In the Smiling Friends episode "[S1E5] Who Violently Murdered Simon S. Salty?", the titular character actually died of a heart attack from a poor diet rather than being murdered by his restaurant mascots. Despite this, the mascots, including Mustard and the Ketchup, attacked and "killed" his corpse throughout the night.
Detailed information about the episode, including character descriptions and a full script, can be found on the Smiling Friends Wiki and the Adult Swim Wiki . Simon S. Salty | Smiling Friends Wiki [S1E5] Who Violently Murdered Simon S. Salty?