1 Monty: Good news, dad! Miss Thoroughgood has responded to our telegram.
2 Monty: Wait. Did you start breakfast without us?
3 Prof. Jones: No, not at all, Junior.
4 Monty: What's all this then?
4 Prof. Jones: I'm just finishing off my midnight snack!

I'm not sure how many people have "midnight snacks". I've never had any inclination to do it myself, nor has anyone in my immediate family, so as far as I can tell maybe it's one of those things that you only ever see in fiction. I first came across the idea in Blondie comics, in which Dagwood Bumstead is a famous big eater who often raids the fridge in the middle of the night.

Then of course there's that other well known comic strip eater, Garfield, who has also perpetrated the odd midnight snack.

I seem to recall seeing Scooby Doo and Shaggy making late night snacks as well - usually before getting interrupted by the "ghost of the week" who turns out to be Old Man Smithers and who would have gotten away with it if not for those pesky kids.

And in more recent times, Nigella Lawson has become known for ending her cooking shows with herself raiding the fridge in the middle of the night.^[1]

[1] This essentially qualifies as fiction too, as I'm pretty sure she doesn't really have a TV crew camped out in her kitchen all night just hoping to catch her in an unplanned late night snacking expedition.