twosome and horse fish

Tonight at my sister's house the bachelor was on t.v. and Peter says
"Oh look at that guy with those two girls! What's the hell's he gonna do? Go have a twosome?!"
"A twosome, Peter?"
"Well actually it's called a MENGAGE A TROIS!"
After we stop laughing I say
"You know Peter, that's actually acceptable in some cultures, to have two women."
And Peter says
"You know male horse fish carry the babies!"
"Horse fish, Peter?"
"Yup! The guys."