My wife and I have had a couple experiences that might be of interest. The first time happened with a couple drunk evenings and I am in the midst of the second experience.
A few years ago I had a friend who hate dated my wife in high school and we started to see each other more on the weekends. I could tell there was some flirting still going on between them. One evening while having some drink we decided to play some card games. This lead to playing strip poker. My wife is reserved and shy naturally but the combination of alcohol and two men who said she was hot got her more daring. It began with just getting down to our boxers and her thong and bra. We kept playing and soon her bra was off but she was covering herself with a pillow. That first night she flashed her tits at us and afterward she and I had crazy sex. A month later her we were again playing cards and we just moved right to strip poker. This night I knew was different when she showered and shaved her pussy before our friend came over. Soon we were all naked and wondering what to do next when she mentioned we should keep playing and the loser had to do a dare. The dares started with us being able to touch her tits and her touching our cocks then it moved to fingering her and sucking on her tits. My friend dared her to suck his cock which mostly just licked like an ice cream cone. She then dared him to lick her pussy. He didn't even hesitate. He started by sticking his tongue up her pussy and really licking her. I watched her eyes roll back and catch her breath. Watching my wife have an orgasm was mind blowing. I had nver been so horny. After her orgasm I saw her climb on top of him and start rubbing her pussy lips against his cock. They were really grinding when I heard her say Whoa. She climbed off him and gave him a kiss and then climbed on top of me. Her pussy was soaked. She said his dick had just pushed into her opening and she wasn't sure she was ready for the next step. I told her no problem and we fucked like crazy in front of my friend who was jacking himself off. It was a night that still gets my wife excited whenever we bring it up.
