Foy is the acronym for Fountain of Youth. It is a relatively common trope in babyfur content involving Age Regression.

Similar to the Juice That Makes You Cum tag, the Foy text must be visible at least once in a recipient somewhere in the picture. Otherwise the tag is not applicable.

If there is a Fountain of Youth in the image, but no bottle of "FoY", you may only use the Fountain of Youth tag.