This bet comes from one evening when we were staying at a smaller hotel chain out of town.
After a nice dinner we went back to the hotel and went to the small little bar that they had. They had music playing and a pretty good crowd of people. The bar backed up against the swimming pool on the other side. If you were sitting at the bar, you were facing the swimming pool outside. You couldn't see the pool at the bar because of the wall but there was a window off to the side of the bar that looked out towards the pool.
Since there was no seating at the bar, Stacy and I ordered our drinks and went and stood by the window. The pool area was somewhat dark but the pool light was on, making the pool light up. As we were standing at the window, I told Stacy what a nice view of the pool it was. She looked out and said she could barely notice it was out there.
I told her, "I bet if you were skinny dipping we would notice!"
After a few drinks we decided it was time to go. The crowd was still pretty good when we left. It didn't look like anyone took our spot standing by the window. As we walked out, Stacy said something about how nice the pool looked. At that point, I told her she should go skinny dipping.
At first, she just said, "No".
Then I said to her, "You said no-one would notice from the bar, I bet you won't skinny dip for five minutes!"
That was all it took. Next thing I knew, she was off to the side and started stripping off her clothes and telling me to have the room key ready when she was done.
The window of the bar was down at the end of the pool where the pool stairs were. I went down by that end so I could see inside the window from an angle.