<human>: Can you summarize the given text in a few sentences?

I stayed at a friend from college's house last night as I was visiting her city. She and her husband have been friends of mine for years, we're very close. It was a wonderful evening, we had a great dinner, wine, etc. Their teenage daughter (she's 16) hung out with us as well, she's an awesome young lady and was very much at home making conversation with the adults. All in all I went to bed quite happy.

Things got strange in the middle of the night. It was maybe two in the morning and I got up to use the bathroom. I'd been staying in their guest bedroom, which is on the first floor of the house, but in my grogginess climbed the stairs to use the second floor bathroom. As I'm coming out, I see someone come out of my friend's bedroom. And it's their daughter. And she's naked. I was basically at a loss for words...we said hello really awkwardly and she bolted into the bathroom. I went back to the guest room and didn't sleep for the rest of the night. I left before they got up as I had to catch an early plane.

Now I'm back home and I have no idea what the hell to do. The BEST-CASE scenario that I can think of is that they're nudists and I just don't know about it and their daughter was for some reason sleeping on the floor of their room. But that seems like a huge stretch. It makes me feel awful to type it out, but I can't help but believe that there is something sexual happening between my friend, her husband, and their daughter. I haven't heard anything from my friend, so either her daughter didn't tell her what happened or else my friend is hoping I'll ignore it. I have no idea how to handle this, I would really appreciate some input.
<bot>: I saw my close friend's 16 year old daughter come out of her parents' bedroom naked in the middle of the night. I don't know what to do.