Nightmare Fuel / The Hitchhiker's Guide to the Galaxy

• The original radio show features the Haggunenons, a species with an Unstable Genetic Code which allows them to shapeshift. But as the guide says, "they do this with such reckless abandon that if, sitting at a table, they are unable to reach a coffee spoon, they are liable without a moment's consideration to mutate into something with far longer arms ... but which is probably quite incapable of drinking the coffee." This makes them insecure, so they create massive warships and declare war on all the "filthy rotten samelings". What does the guide say on how to deal with them?
  "Run away terribly fast."
  • In Fit the Sixth, our heroes accidentally board a Haggunenon ship en route to a big space battle. Then they realize one could be with them right now. Ford notes that it could even be the chair with two headrests that Zaphod and Trillian sat in earlier, which leads to this exchange:
  Trillian: It's very uncomfortable - I'd prefer something with far longer arms.
  Arthur: But which is probably quite incapable of drinking coffee.
  (Beat)
  Zaphod: ...What did you just say, monkey man?
  Ford: Are you sure those are headrests? They look an awful lot like eyebrows to me...
  • It turns out most of the things on the ship are actually Haggunenons, one of which turns into a perfect carbon copy of the Ravernous Bug-Blatter Beast of Trall and eats Zaphod, Marvin, and Trillian.
• Remember the bowl of petunias that materialized over Magratheia and thought "Oh no, not again"? It turns out that was actually Agrajag, a being who was repeatedly killed over various lifetimes by Arthur Dent (sometimes by accident), and the repeated deaths have warped his mind.
• In the radio version of the fifth book, the Guide Mk. 2 manages to take over the credits. This is more creepy than it sounds (especially if you know how Mostly Harmless ends). Then the regular announcer returns, and instead of the usual gag at the end, he advises listeners to "trust the bird".
• The Kriketeers, a race of polite, friendly, charming, cheerful, whimsical people who never realised there was a world outside their own, and on doing so and seeing the sheer size of the universe have the most understated mass Freak Out ever put to print.
  "It'll have to go." They said.