Board Thread:The Reference Desk/@comment-24894325-20170326143635

The text of the comic was not enough for me to figure out what it refers to: "An old friend of mine--well, enemy, really--once tried to create a new universe to rule maniacally--or something like that--I lost interest early into his monologue. I put a few minus symbols before his calculations, so it ended up a wee bit smaller than he planned. I've got it in my pocket. An entire universe all to himself, no other life-forms whatsoever. If you listen closely, you can hear him calling me all sorts of names"

- Twelfth Doctor tells this holding the universe in question between his thumb and index finger.

In the absence of proper names, I couldn't find this story. If it rings a bell for anyone, help is appreciated. 