Without moving at all, we were fucking each other. Her cunt was rhythmically squeezing my cock. The vibration of the train was buzzing up through the base of my shaft into her, and every bump drove me a little deeper.

I had to bite my lip to keep from moaning so I didn't draw the attention of the other passengers. We were fully clothed and she was sitting on my lap, facing away from me, pretending to look at her phone. Her skirt was spread over my legs, which kept us from being too obvious, but I was still nervous.

Every seat on the express train was full. The aisles were packed elbow-to-elbow with a mix of fans heading to the game and commuters heading home after work. We were in the single seat at the back of the train car — the one mounted sideways between the last row of seats and the rear wall. Everyone standing in front of us was either talking or looking at their phones. No one seemed to notice what we were doing.

I had definitely noticed when she got on the train, though. I always did. She rode the same train home as me, and I watched for her. She liked to wear short skirts and heels, and her strut was so exaggerated it was almost comical. I expected kettle drums to start playing like in cartoons. boom-ba-boom-ba-boom.

She had been standing in the aisle near me when the mob of sports fans got on the train. The crush of bodies pushed her back until she was standing directly in front of me. She was wearing a flared knee length black skirt and a thin pink tank top. The red straps peeking out hinted at the lace bra she wore under it.

I was looking at her ass, wondering what kind of underwear she had on, when someone shoved their way into the train at the last second. That caused a ripple effect in the crowd that ended with her being jostled back, and falling onto my lap. Before she could stand up, the crowd filled the space she had been standing in, and the train started moving.

She looked at me and shrugged, and I shrugged back, trying to act casual. She put her bag on her lap and continued looking at her phone. It was clear she had just come from her office. I could see a blazer folded on the top of her bag. A few strands of carefully pinned hair had slipped loose around her ears.

I tried to ignore that, to not think about the hot girl sitting on my lap. Although the pressure of her ass against my crotch, combined with the vibration of the train made it difficult. I felt my cock stiffening. I kept my hands pressed to my sides, deliberately not touching her. I caught myself staring at the nape of her neck, imagining kissing it, and quickly looked away.

I watched the scenery passing by and tried to think innocent thoughts, but it was useless. Every bump, every jostle, every movement of the train made me more aware of her. I tried not to move and hoped that my growing erection pressing into her rear wasn't too obvious.

Suddenly, without saying a word, she shifted her weight and pulled the back of her skirt out from under her with one hand. I looked around, shocked, but she wasn't making eye contact. No one else was either. Due to our position on the train the only people who could have seen anything were standing right next to us. They were all either facing away from us or staring at their phones. No one had seen what she did, and if they looked now, they probably wouldn't notice her skirt bunched up a bit in the back.

Then she shifted in my lap again. She moved her hips in a circle, grinding against my cock, now nestled between her cheeks. I could't believe this was happening. Certainly I had fantasized about her, but I never imagined anything would actually happen.

Taking this as my signal, I checked again to make sure no one was looking, then reached between us to undo my pants. She lifted herself just enough let my hand in. I unbuttoned my pants and opened them enough to free my now painfully erect cock. I used my thumb to press it forward against her ass.

She sat back down, moving so my cock ended up jutting between her thighs. The sensation was unexpectedly intense. Only the thin fabric of her panties separated us now. I could feel the heat of her pussy through it, and the lace texture teased me mercilessly. She squeezed her legs together to increase the pressure, causing my cock to throb in anticipation.

For several minutes, we sat like that. My cock nestled between her thighs, rubbing against her panties with every bump of the train.

I scanned the faces of the crowd around us, but I was mostly focused on what was happening under her skirt.

Just as I began to wonder what would happen next, the train went into a tunnel. She took advantage of the momentary plunge into darkness. I felt her lift up just enough to pull down her panties, then sit back down on me, all in one quick movement. No one seemed to notice, and she went right back to her phone. Only now instead of her panties, I was pressed directly against her pussy.

She shifted her weight and I let out a little gasp when I felt the heat of her lips slide smoothly along my shaft. She was already soaking wet. Apparently I wasn't the only one aroused by our forced intimacy.

As subtly as I could, I tried to wiggle around so that I would slip inside her. It didn't work, but it did succeed in rubbing more of her juices onto my head. I was starting to get frustrated when she took action. She pretended to sneeze, and used the sudden motion to part her legs and lift up. When she came back down, I felt her lips wrap around my cock.

I froze, terrified that everyone would suddenly notice what we were up to... But all that happened is someone said "Bless You," without even looking. She said thanks, and ground her ass firmly against me, sliding my cock a bit deeper in her pussy.

The angle was awkward, we could barely move for fear of being discovered. I can't have been very deep inside her... but it didn't matter. We were both so turned on by the idea of what we were doing that we might as well have been screaming in pleasure. I couldn't believe how hot her pussy felt, and my cock was throbbing in excitement.

I was struck by how calm she seemed. My hands were firmly gripping the side of my seat, afraid if I touched her someone would see. She was still sitting with her bag in her lap, staring intently at her phone. I doubted anyone else had noticed she'd been staring at the same screen, or that she was biting her lip.

We didn't move much, but because of the motion of the train, we didn't need to. Every jostle and bump sent a shock of pleasure through me as I slipped a little bit in or out of her. There was a constant, rhythmic vibration from the wheels on the tracks. It was increasingly difficult to act like nothing was happening.

As the minutes passed, I grew more sensitive, building towards to an orgasm. I felt almost painfully hard. I imagined the head of my cock, swelling larger and spreading the tight walls of her pussy. I felt her soft, wet lips wrapped around the base of my shaft, and bit my tongue to keep from moaning.

I had no way to tell her what was going to happen, and even if I could, there was nothing we could do about it. The realization that I was about to cum inside this woman I had crushed on for so long finally pushed me over the edge.

I breathed deeply, and then suddenly my entire groin was pulsing as I came. I felt her startle slightly, and then press her ass firmly against me as I pumped my cum into her pussy. I wanted desperately to wrap my arms around her, squeeze her tits and bite her neck while I came. Instead I held as still as possible, my eyes shut tight, feeling every hot, throbbing spurt.

After a minute it passed, and I released a breath I hadn't realized I had been holding. Looking around nervously, I saw that no one had noticed. The noise of the train and surrounding conversations had effectively hidden us in plain sight.

Even more surprising was that we were coming into the train stop. Somehow the entire half-hour ride had passed. I was grateful that the timing had worked out. She stayed sitting on me as we pulled into the station, even when my cock softened and slipped out of her. I could tell we were both a wet mess down there, but there was nothing we could do about it just yet.

Once the doors opened, everyone was in such a hurry to get out that no one was looking as she stood up. I watched her pull her panties (lacy black, I now saw) back up. Her skirt slipped into place, concealing that her thighs were slick with her juices and my cum. I had to move quickly to button my pants before anyone saw me. They were a bit wet, but nothing too noticeable, I hoped.

I made eye contact with her as we walked off the train, unsure what, if anything, to say. She just winked and walked away. I laughed and headed for the bathroom to clean myself up.