We all have pretty much the same stuff--ears, toes, fingernails, chins....and nipples. Therefore, in English, we have a word for nipple: it's called "nipple."
But not in Spanish. Just to confuse Spanish language learners, they made up TWO completely different names: "tetilla" for a those found on a man; and "pezon" for those found on a woman. And to further complicate things--
You know that every noun in Spanish has a gender, unrelated to what it is. For example, "casa" (house) is a FEMININE noun ending in the letter "a." "Aeropuerto" (airport) is a MASCULINE noun ending in "o." With me so far? So the noun "tetilla" (MAN'S nipple) is a FEMININE noun, even though the little buggers appear on a man's chest. And...no surprise here..."pezon" (WOMAN'S nipple)is a MASCULINE noun. Go figure. Gender bending at it's most confusing.