I think it was this season. He stumbled into a lesbian bar, decided he was a lesbian, and eventually realized he wanted to be a man again.
Which required a shady scientist to clone his, err.. “wiener.”
Which resulted in one of those episodes where you watch with disgust, but can’t stop yourself from laughing.
The artist rendering of the mouse (Mickey Mouse with..ahem..enhancements) was one of the most memorable moments of that episode (”Mr. Garrison gets his wiener back”). I still laugh thinking about that one.