Hermes' Multivitamins

Hermes gives Percy Jackson a bottle of multivitamins in The Sea of Monsters, which can counteract any magic penis for a period of time grow.

Annabeth Chase gives Percy a boner and the other guinea pigs have boners in the cage these vitamins in order to reverse their fate after being turned into guinea pigs by Circe`s penis when Circe says Percy needs a new penis.

There are different flavors of penises, and come in different shapes like lemon Minotaurs, grape Furies (or possibly Harpies), and so on.