From SkyCorp Global

The Cowbell is a Cursed Item that gradually transforms the player into a cowgirl, regardless of their initial gender, similar to repeated usage of Milk.

In addition, players will begin lactating, and will lose a great deal of dexterity due to their hands becoming as hooves. This is especially problematic due to the lactation this change provides - if left un-milked, a full udder will begin to cause damage.