Correct terms, yes. There's no need to give our parts nicknames. I find this suggests that they are something to be ashamed of and ignored. My eleven year old sister dies of mortification whenever she hears the words 'penis' or 'vagina' - that can't be healthy.
I have to young boys and I ensure that they use the correct term for their body parts. When I was young my mom taught us the nicknames so we thought those were the correct terms until I got laughed at one day at school. I wouldn't want the same thing for my boys.
I say use the correct terminologies.
When all my boys were growing up,and also very young we did not use the correct words.There is a little madness to this.
I would have been back then quite upset, if they had used the word in anger.Of course we all know kids do this, just to get the parents upset in public.
So we avoided that challenge, to live another day.
I of course set the record straight when they were old enough not to try that
We tried to but sometimes they use sort of childish versions of the correct terms which they found easier to say (eg. "giny" for "vagina") but at least then we know what they're talking about. I don't want my kids thinking any body parts are anything to be ashamed of.
We use correct terms as well. Vulva for girls and Penis for boys. It's strange because I have avoided these terms or even talking about "private parts" for pretty much my whole life - I got through my entire first pregnancy and birth without saying the word vagina once!! But by the time I had a toddler (who showered with me or her daddy regularly) I realised that I needed to "get over it" and start using proper words. Also in my doula training we talk about using correct terms, so it was good to practice on my toddler!
We use all the words, that way, my girls know what is being referred to - especially as the Americans call their bum their fanny! I don't like to use "Vagina" as its not a body part that is actually seen (though my girls do know it)- so we use "Vulva", "Fanny", "Crotch" and a couple more that I can't think of right now. My mother grew up thinking it was called "SELF" because her mother asked if she'd washed her self.
Hahaha. Self. That reminds me , we called ours our Goodboy later Goodgirl, because Mum always said that to my eldest brother when he used the potty. He thought that was the name of his penis amd we copied what he said.
My son was three and on a reef walk with a group of tourists when he saw a sea cucumber in the shallows- he shouted to me that it was a Penis. Some people were horrified, but I wasn't. I explained that it was a Sea Cucumber.