I just have a wife who is willing to go with almost anything as long as there is a very, VERY strong "innocence" to it. I think she is just super competitive and if I ever say anything like, "I didn't think you would do it," then she's all in. Maybe it's the middle child part of her coming out. This got her into some naughty trouble in college, I know. People would say, "Are you going to be the only girl hiding her boobs for mardi gras?" And out they came, and she outdid the other women, I was told.
If I told her to walk around the house topless when her brother was there, she would say no way. But if I tell her to wear pajamas and let her boobs accidentally fall out, she doesn't see any reason not to, because they are just pajamas, right? And if a boob falls out, well pajamas are just like that. Wear a bra under pajamas? Why would I walk all the way back upstairs to take it off? It's my house, right? Those types of things... But if I weren't around at all, I don't think any of it would happen. She recently stayed the night at a friend's house. The husband was home, and my wife said she even slept in a bra those two nights. I believe her, sadly.
She and I are very compatible like that--the whole "innocence" thing--so I know just what to say and how to say it to get her to give it a shot. Toss in a dash of dare, and she's in.
Like way back, long before kids, we shared a hotel room with her mom, and I got her to have sex with me with her mom in the room because I said, "If your mom sees us and asks, just tell her we are trying to give her the grandkid she has been begging for for three years." My wife thought that was a great idea, and she was all into it. Sadly, her mom didn't catch us (her mom was in the bathroom around two corners, but awake), so I have no idea if my wife would have actually kept going or stopped. I hope she would have kept going.
We did it again while her mom was sleeping, but the risk was extremely low at that moment. (Then we did it a few months ago when her mom was using our tub, but my wife could hear enough to remove all risk.)
But, my wife was like this with her previous two boyfriends, as well, which is how it all came up. When I met her, *I* was the prude, ha! When my wife suggested having sex in public the first time, I was mortified! Then she told me the story about having sex with a boyfriend in front of his friend because "there just wasn't anywhere else to go." I was still mortified! Then we did it in public once, we didn't get caught, and we did it again and again, and the rest is history.