The erection, representation, display and use of often grotesque figures and objects to protect against or ward off misfortune, thieves, enemies, sorcery, witchcraft, evil spirits, bad luck or the Evil Eye...which might be, or be induced by, envy.

At Leptis Magna in Syria a doubly-apotropaic sculpture has been unearthed: a bull-legged phallus whose penis is squirting semen into (blinding) a vaginesque Evil Eye which is carrying or being devoured by a ?scorpion.

photo by Sacha Coachman

Maybe a thousand years later at the church of Sant Pere de Galligants in Girona, this fork-bearded, tongue-protruding 'merman' was carved with great skill, and decoratively performed (or rehearsed) the same apotropaic function.

Compare with an ancient Egyptian, exhibitionist image of the god Bes (from the second millennium BC) in the Egyptian Museum in Turin, and with other examples of tongue-stickers on another page.

The praying figure below, dating from around 1200 (if not earlier), reminds us that the gaping, eye-shaped vagina, while warding off the evil eye, also is the portal to hell.
It is not likely, however, that its head was [dis]graced by a protuding tongue.

Sens, cathedral of St Etienne.

Turning to the natural world, the simplest examples are protective false eyes, on butterflies, for example, whose forerunners in evolution were the eye-spots developed by some hexapods to encourage predators to think they were being watched by their quarry.

By far the oldest (universal) human behaviour patterns and displays are the protective hand, beard display, breast presentation, pulling a face or mouth-pulling, genital and pubic display, arse-display, presentation of a grotesque mask, milk-squirting, erection of 'sentinel' or guardian figures, and sticking out the tongue.

Some vulva-showers are depicted in the emphatic action of pulling up a dress, as at Fuentidueña (Segóvia) which is yet another figure whose head has been removed. See also Lammas in Norfolk, England.

Some links:

https://www.ancientworldmagazine.com/articles/phallus-evil-eye/

https://robin-de-puy-american.wetransfer.com/episode/10

Protecting_the_Troops_Phallic_Carvings_i.pdf