For my son, we have not really referenced to the correct scientific names... We refer to them currently and during his potty training as his "Peeper" and "Bupp" so this way neither of us are embarrassed if he decides to announce it to the world as many toddlers and preschoolers enjoy when they learn a new word. (when he caught sight of hubby or me naked and asked about ours and why they are different, we still referred to them the same way, and told him they are different because Daddy is a boy, Mommy is a girl and we are both older than he is - meaning his will look like Daddy's when he is bigger. He was happy with that answer and did not pursue any further, and we did not feel like we were lying to him.)
Hope this helps~ as it can be a sticky situation! :)