[Obironic]

My wife had an experience when she was younger.

She had been on holiday with her family (years before we met) somewhere in France - a bit of a rustic place, but they had a swimming pool. Each morning after swimming, she would leave her yellow swimsuit in the sun to dry.

Anyway, after a couple of weeks of this, it must have faded. No one in her family had brought it up, so she was none the wiser.

Cut to a couple of weeks later and some of her school friends arrange to go to the local pool - she grabs the yellow swimsuit and joins them.

She finds out the suit has gone transparent when she is stood at the side of the pool, dripping wet and one of the boys from her class yells from the other end of the pool that he can see her nipples.
The way she tells it, everyone turns and stares at her, she panics and covers her small breasts (one in each hand) and just stands there.
After (an undetermined) amount of time, he then shouts "I can see your bush too"

Apparently the story made it round school by the first day back and everyone knew about the incident. It is her most mortifying experience, but it turns me on no end. It's tricky to push for more details as she still gets embarrassed, some 20 years later, but I still think about it every now and again - wondering how many of her classmates got to see her nipples