(noun) when a grown female (meaning she is of age, perverts), has a rather small nipple, it can be referred to as a 'boy nipple' (hense the fact that most nipples on most boys are smaller). also known as a baby nipple, dime sized nipple, etc.
I had this dream last night that my dad caught a glimpse of my boy nipple! I was so embarressed because now he's not sure if I am a daughter or a son! WTFFFFFF!!