First attempt at this so be gentle. I had been seeing this girl for a while. Our sex life was fantastic, nothing was taboo. We had gotten a lift with a friend to the local supermarket but as she had a lot more shopping to do, myself and then girlfriend went back to wait in the car. Not entirely sure what came over me but I started talking about sex as we sit in the car park. She was in the front and I was leaning between the two front seats from the back. I started talking about what I was going to do with her when we got home. She started to squirm in the seat as I talked about her being fucked hard as soon as we were alone. Suddenly she says she can't take it anymore. She lifts up her skirt, slides her thong to the side and slowly slides her fingers inside her now soaking pussy. I keep talking about what I'm going to do with her and she picks up the pace. She takes her fingers out momentarily and demands I lick them clean, before entering a second finger inside herself. A number of people in cars close by come and go with their shopping but nothing is stopping her now. I'm whispering in her ear as she is rubbing her clit and fingering herself furiously. There's now a visible wet mark on the seat of the car but she continues on. I reach in and start fingering her too. She now has four fingers inside her. I can see our friend leaving the shop and is on her way to the car, but my girlfriend begs me not to stop. I start fingering her furiously until I feel her tighten up as she cums. She adjusts her skirt just in time as our friend opens the boot to put away the shopping. Needless to say we had a marathon sex session when we got home.