Have not yet been in an embarrassing situation myself ... yet (lets keep it so), but there is a story about my SIL that was a bit embarrassing for her (and a bit flattering for me).
The 1st time my SIL got to see me naked, was during a weekend away with wife, her sister and BIL.
In the evening we took a sauna and the guys remained naked too cool down, our wives did join later that evening (full story on that is already written in another thread).
And to be honest, at first I had a hard time to keep my dick soft, so SIL got to see it fully erect.
The next morning, wife and her sister were preparing breakfast while the guys were doing some other chores around the cabin. Till one moment I heard my wife laughen really hard and calling me into the kitchen. BIL came also into the kitchen where we found my wife still laughing and my SIL with a bit of panic on her face. As soon as we walked in, my wife blurted out "you wanna know what my sister just told me (in confidence, but my wife couldn't wait to tell me, ignoring her sister). She thinks my husband has a really long, thick good looking dick".
After that, SIL didn't know where to look, and both BIL, my wife and I started laughing.
Funny thing is that both BIL and I are about same size and thickness, only difference is that BIL is cut and I'm uncut. But apparently, SIL likes the sight of an uncut dick.
Then there is also an embarrassing story about my wife, but considering the rules, probably not suited to post.