SKAGRA: “Take over the Universe.” (laughs) How childish. Who could possibly want to take over the Universe?

THE DOCTOR: Exactly! That’s what I keep on trying to tell people. It’s a troublesome place, difficult to administer, and as a piece of real estate it’s worthless because by definition there’d be no one to sell it to.

Doctor Who (1963–1989) British science fiction television series, original run (BBC)

17×06* “Shada,” Part 5 (1980-02-16*) [w. Douglas Adams]
    (Source)

(Source (Video)).

This serial was intended to close out the Fourth Doctor's Season 17 (and Adams' story editor role on the show), but was never completed due to a BBC strike, with only about half of the filming accomplished. This scene was not filmed at the time, but exists in the script. The date shown is what would have been broadcast schedule for this Part 5 of 6.

It was remade, with the Eighth Doctor, as an audio play by Big Finish Productions, webcast on BBCi in 2003. The BBC released a version completed with original actors, sound equipment, and limited animation, and released it to DVD in 2017. An enhanced animated version was produced in 2021 (the video source linked above is from that version).

More information on the episode here and here.