This happened some time ago, when I was a student. I was a member of the climbing club, and we had our annual dinner at an inn up in the hills some way away. Those of us too poor to pay for a bedroom all crashed out on the floor of a function room, some more drunk than others. I suppose there was about 20 of us, 50:50 men:women, some married, some playing the field, some unattached.
I laid my sleeping bag in the middle, and what with the alcohol and the lateness I was dead to the world in 4 seconds flat. I awoke at some time in the night; it was pitch black and I lay listening to the small sounds of breathing around me, wondering if I would have a headache later on. I put my arms behind my head and stretched - the floor was none too soft for sleeping on. My hand encountered another hand. I made to pull away but the other hand caught at my fingers. It seemed to be a female hand, as far as I could tell, but I hadn't a clue who it belonged to. I tried to remember who had pitched their bag behind me, but with no success.
The cool fingers of the mystery woman explored my hand and wrist, then I felt her other hand touching me. She pulled slightly, and I got the message and wriggled up out a little so that our hands could slide down each other's arms. It was quite arousing and I had a sudden worry that it would turn out that She was another man. However that didn't stop me moving slowly across the floor, as (s)he did the same. Presumably (s)he could tell from the hairs on my arms that I was male. I paid more attention to what my fingertips were telling me and reassured myself that (s)he had extremely smooth and feminine arms for a man.
We touched each others faces and gently explored. Her fingers were incredibly gentle yet bold. As she reached my lips I took hold of her fingers and licked them, feeling her doing the same to mine. Her nails were short and rough; well, in a climber that is no indication of gender.
We were now lying head to head with our arms parallel, and I felt her shuffle further towards me. Her wandering hands continue to work their way down my neck and chest, and I followed her lead, trembling at what I might find. I breathed a silent prayer as I touched soft yielding mounds, warm from the confines of her sleeping bag. I sought out the nipples, bolder now, and massaged them softly. They grew hard slowly, and my cock, already swelling with the excitement, followed suit.