I know something like that happened in Scooby Doo, Mysteries Incorporated, because Freddy was a real mess by the end of the series.
But its just a common trope
Not the one I'm thinking of. I'm thinking of a live action scene.
Bit late to replying, but there was a UK Yellow Pages advert in the 1990s that followed this same plot. Maybe that?
This scene happens in Fionna and Cake but that's recent
Similar joke but not it. Never seen this show before.