I used to live alone and I rented an apartment with about 100 other tenants. One of those tenants is a 33/34-year-old woman named 'Carol' who lives across the hall from me. She's about 5'6', 120lbs, short sandy blonde hair, brown eyes. She is really beautiful. She's a professional working woman (based on how she dresses) and she has a live in boyfriend.
The building has a parking garage and my assigned spot is on the third floor, hers is on the second. I hopped on the elevator one afternoon with a couple of bags of groceries and she hopped on the same elevator a floor higher and we shared the elevator up to the third floor.
She was wearing the most wonderful perfume. Couldn't figure out what it was. Anyway, the smell plus her outfit (sophisticated, professional) plus the fact that she is beautiful got me hard. She walked out of the elevator first and was about three paces ahead of me the whole way to my apartment. She has the most beautiful body and the sexiest ass and I had the perfect view as I walked down the hall.
I got to my apartment door, put down my groceries, unlocked the door and entered my apartment. I put the groceries away, but I could still smell her and I was still very aroused. So I did what most men would do in that situation.
I sat on the couch in my living room and started to remove my clothes. After I stripped down naked, I began to masturbate, fondling my erection and balls with my right hand while my left hand caressed parts of my body (my nipples, inner thighs, etc.). I wound up lying on my back on the floor in the sit up position (knees bent with my feet next to my ass). I would hold my right hand still and using my feet and hips, I would thrust my pelvis in the air into my hand. As I was having sex with my right hand, I would let out a soft moan, every once in a while moaning out Carol's name. As I got closer to orgasm, my moans got louder and Carol's name became more prominent.
At the moment of truth, my door opened and Carol walked in! I was looking up when I saw her and we made eye contact for a moment. I saw a woman who was surprised/shocked/astonished/embarrassed about what she saw. What she saw was a man at the height of his pleasure while looking at the woman of his fantasies. What she ended up seeing was me on the floor shooting cum all over my belly as I was calling out her name. She knew she walked into something awkward and took a step back and tried to discreetly close the door behind her as she left.
I would see her in the hall or getting the mail and we'd always have an awkward moment. If there were other people around, she would usually make some sort of comment about it that only the two of us would understand. If it was just the two of us she'd be a tease asking how my right hand was doing with a giggle and smile. One time she even gave me her lingerie catalogue. Carol moved out later that year and I haven't seen her since. She always has a special place in my heart and is the biggest starlet in my fantasy life.