Star Trek: The Animated Series, Series 1, Episode 6.
First broadcast on Saturday 13 October 1973.

This week, crudely-drawn slow-moving simulacra of the Enterprise crew interact listlessly in a crudely-drawn slow-moving simulacrum of Star Trek. Except for the shapeshifting red octopus, which is awesome. Meanwhile, Joe drops £2.50 renting a Star Trek episode whose budget was nearly ten times that, adjusted for inflation.