Tribbles. So infamous even non-Trekkies know the name. What are they? Little balls of purring fur born pregnant with a litter of ten which they birth after digesting enough food. Also, they’re Klingon detectors.
That begs the question: why were Klingons made into such an obviously alien species after The Original Series? You know, with the oversized wrinkled foreheads and all. McCoy figured out you just had to keep a tribble’s diet small to forestall their reproduction without starving them to death and you have instant Klingon detectors for all those situations when you’re worried about Klingon spies. If they had stuck with that, there would have been plenty of opportunities to play with the fact that Klingons look like humans.
Ugh. Anyway. Scotty holding Chekov back when the Klingon insults Kirk, but then turning into a Whirling Dervish of punches is classic. Also, Kirk’s use of The Look when he’s swimming in tribbles had me in stitches.
Conclusion: I made a book of Mother Tribble’s Nursery Rhymes.