Coquetear, the Spanish verb meaning “to flirt,” comes from the French coq which means “cock” — in both senses — from which we also get the English word cock, albeit with a slightly different spelling.
It’s not that hard to figure out how a word that means “penis” came to mean “flirt” — but it is easy to smile every time you remember why.
From the same root, we also get the almost-forgotten English word for “flirting,” coquetry.
The c-q to c-ck mapping is clear between both words.