From Medium.com comes this lovely little explanation of why we say certain things in a certain order.
Ever wonder why we say tick-tock, not tock-tick, or ding-dong, not dong-ding; King Kong, not Kong King? Turns out it is one of the unwritten rules of English that native speakers know without knowing.
The rule, explains a BBC article, is: “If there are three words then the order has to go I, A, O. If there are two words then the first is I and the second is either A or O. Mosh-Mash, chit-chat, dilly-dally, shilly-shally, tip top, hip-hop, flip-flop, tic tac, sing-song, ding dong, King Kong, ping pong.”
There’s another unwritten rule at work in the name of Little Red Riding Hood, says the article.
“Adjectives in English absolutely have to be written in this order: opinion, size, age, shape, color, origin, material, purpose — and then the noun. So you can have a lovely little old rectangular green French silver whittling knife. But if you mess with that word order in the slightest you’ll sound like a maniac.”
That explains why we say “little green men” not “green little men.” And if you think you’ve outsmarted the rule with “big bad wolf,” because its order breaks the rule, which should be “opinion(bad)-size (big)-noun (wolf).” You didn’t, because the first rule about the I-A-O order supersedes this secondary rule.
That rule seems inviolable: “All four of a horse’s feet make exactly the same sound. But we always, always say clip-clop, never clop-clip.”
This rule even has a technical name, if you care to know it — the rule of ablaut reduplication — but then life is simpler knowing that we know the rule without knowing it, isn’t it?