boys don't have a vagina, thay have a mangina
ok, so couples do tend to come to a comfort level in how they refer to their own and each other's parts. My x-wife used to object if I said things like weiner or pecker because she felt such silly terms dimminished it's significance.
I never named my penis, I always thought that was silly and undignified... but that's just me.
I have a friend who actually gets annoyed if you refer to her vagina as anything but a cunt. Some people take such huge offence to that word (and sorry if you do) but she finds all the cutesy words to be offensive.
you're right though, it is an interesting topic. So many names and even more if you delve into other languages.
Pflaumen for instance. It's german for plum and also an off-colour term for a vagina. Guess it makes about as much sense as calling it a pussy or a susie