When I was about 14, I was in a car full of teens being dropped off after church. The car was packed and a girl who was built like that was sitting on my lap! She was older, maybe 17, but I kept cool about it and behaved like a gentleman.
I had a similar situation around the same age. As I recall, my body had already betrayed me, but the situation was unintended and we both acted with aplomb---or at least she did and I tried my best.
B.H.Wilson 