Before you brought up the Spanish examples, I was thinking of French. Son vagin, sa verge. Yes, "vagina" is grammatically masculine and "dick" is grammatically feminine. You can see that from the possessive pronouns, but the pronouns work like they do in Spanish. They modify the possessed object rather than indicating the gender of the possessor. I can just imagine the French twisting their tongues trying to translate O'Neill's argument.