Another time that turns me on when I think about it was on a train to London one day, I met up with a girl I had been chatting to. We arranged to get on the same London bound train, it was October  time so she had a coat with her. Anyway as we sat together in the two seat she had the coat over our laps. It was only natural my hands should wander up her skirt and press against her mound. She opened her legs slightly and was able to feel the gusset of her knickers and work them to one side. She was dripping with anticipation and all the time just looking out the window. She hitched forward slightly and I turned to face her (she was on my right side) and I was able to slip my finger straight into her pussy. I pretended to nod off, but my finger was working her cunt and clit the whole time. Unfortunately she was not able to cum... But instead she worked her hands over my hard cock. I had suit trowsers on, so she had easy access to me. Unbeknown to her I had gone 'commando' so her hand went straight on my bare cock! She loved it. She squeezed and pulled at me and massaged my balls, which were so so full. I was about to cum and I had to whisper in her ear as I knew I'd make a mess. So she swivelled me around, so my back was facing everyone else and used me as a barrier,  and quickly took my cock in her mouth, with the coat pulled slightly over her and sucked me off, wanking me quickly so I came fast, which I did. She swallowed every drop, and licked her lips before resuming her gazing out of the window, it was so fast yet so hot. Amazing. When we got off at Waterloo, we went to the park area near the south bank and we lay head to toe sort of, so I was able to access her skirt easily. With all the people around I was able to subtlety finger her cunt and bring her to orgasm as she looked up at the blue sky.