Bouba & Kiki (art by Fivel)

https://x.com/merzb0w/status/1481775388762075137

https://en.wikipedia.org/wiki/Bouba/kiki_effect

The Bouba/Kiki effect ... is the tendency for people [across most languages and cultures], when presented with the nonsense words bouba and kiki, to associate bouba with a rounded shape and kiki with a spiky shape.

Bonus: Tom Scott explainer video:

https://www.youtube.com/watch?v=1TDIAObsqcs