People
He looked up at the sky, which was sullen, streaked and livid, and reflected that it was the sort of sky that the Four Horsemen of the Apocalypse wouldn't feel like a bunch of complete idiots riding out of.
— Douglas Adams · Mostly Harmless
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The sky looks so threatening that even the Four Horsemen of the Apocalypse would fit right in. The joke brings a grand image of impending doom down to the awkward question of appearances: under this sky, world-ending riders wouldn't have to worry about looking ridiculous.
Context reviewed