Which episode introduced Mr. Poopybutthole?

Mr. Poopybutthole was introduced in the Rick and Morty episode “Total Rickall.” He appears as a seemingly familiar member of the Smith family during an infestation of memory-altering parasites.

“Total Rickall” is the fourth episode of season 2 and premiered on August 16, 2015. The parasites create false happy memories, causing bizarre characters to appear while the family struggles to determine who is real. Mr. Poopybutthole is treated as if he has always been part of the household, making his presence part of the episode’s central mystery.

The joke becomes especially painful when Beth notices that she has no unpleasant memories involving him. She shoots him, believing he must be a parasite, but he turns out to be genuine. A post-credits scene shows him recovering in physical therapy and apologizing to Beth for making her feel guilty.

The episode was inspired partly by Dawn Summers’ introduction in Buffy the Vampire Slayer, where a new character is suddenly treated as if she had always existed. Mr. Poopybutthole later became a recurring character in post-credits scenes and specials.