The Rule of Ablautreduplication

Why `tock-tick’ does not sound right to your ears.

Ever wondered 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: