My big sister’s idea of playing “house” was me playing the part of a guy who would walk in for breakfast having forgotten to dress after his bath (I would have been five or six at the time.) But we got caught by our parents, who didn’t make a big deal out of it, but Mom told us not to play any more games like that... so I didn’t see Rachel in her birthday suit, at that point.
And even years later, with Dad’s “no shame over what we look like” rules in the house, so that nudity at home was OK, I did see Rachel’s breasts, butt and pubic hair (e.g., her getting in and out of the bath), but not her sex, per se... Dad said if my sister agreed, it would be OK for me to learn about female anatomy by inspecting Rachel, as long as there was no sex play. But both of us told him we thought that was a repulsive idea. Boundaries are there for a reason.
Even when my first serious girlfriend and I started getting naked together, it was holding each other with our clothes off (me on top of her) but I couldn’t really see her pussy, and she would ask me to turn my back for a moment when she was ready to get out from under me, and dressed.
It wasn’t until one night of heavy petting in the car that my girlfriend surprised me by asking if I’d like her to take her pants off and let me explore her, inside. A dream come true, but there wasn’t a lot of light...
A few weeks later, we were actually petting in the car in the daytime, with the seats down... and she was really turned on, partially by the risk of getting caught. I asked her if she wanted me to touch her inside, and the timing of this idea got her nipples hard. She agreed.
She wanted to be undressed, not to undress herself. So I pulled her shirt and open bra out of the way, opened her pants, and got her completely nude. She was lying down, impossible for people in the nearby ballpark to see (I hoped), and as my fingers went in, I got my first in-person look at what I’d been touching. I was surprised by the shape of her labia, which were different from the ones I usually saw in Penthouse.
She didn’t climax... I think both of us were a little too nervous, for that... but it was an unforgettable “first.”