Well, how it happened really was a complete accident. Let me explain.
Dad was retiring from the army after nearly 25 years of service. He had been honourably discharged at the rank of staff Sergeant with a full military pension, including wounding in action benefits, a bullet through the upper arm. Not to mention, a former colleague, who had retired years previously, had started up a successful security firm and had offered my father a position at an excellent salary and benefits package. Because of this, my parents decided to take a long overdue holiday in the Caribbean. Not that I knew that the time, but apparently there was an agreement between them for this trip.
Our first night on the island, dad had too much to drink and the heat didn't help. The next day, mum told me that dad was going to stay behind to sleep it off. On the other hand, we would go to a beach on the far side of the island recommended by the staff. The bus took a long scenic route that wound up into the central mountains that formed the bulk of the island and down to the beach in question.
As we were early, our seats were at the front, so the state of the roads was not as noticeable to us. The view of the island and ocean was too beautiful to ignore.
We spent our day sunbathing on a beautiful white sand beach, swimming in the warm blue sea, exploring the small nearby town and enjoying an excellent seafood lunch cooked over hot coals on the dock. My mum is a beautiful confident woman, 11 years younger than my dad. For her day at the beach, she had chosen the skimpiest of her collection of skimpy bikinis and she was enjoying the admiring looks she got from every man.
We were so enthralled by the slow peaceful pace of life we almost missed the bus back. It was my own fault. I misread the time for the last bus printed on a board at the stop.
Because of my mistake, there was only one seat left. Located right at the back beside the toilet. For some never explained reason, no one was allowed to stand. This meant Mum had to sit in my lap for the entire drive back to the hotel.
The moment bus started its long winding climb into mountains, I knew this was going to be a problem. I was oblivious to the screensaver views out of the right-hand windows for the first time, being entirely focused on the state of the roads. By the feel of it, something was seriously wrong with the suspension back here too.
With every bump, I was getting a face full of mum's thick Auburn hair along with a nose full of the spicy scent she wore. A further complication was that the seat belt didn't reach around both of us. The only thing holding mum in place was my arms wrapped around her trim waist. It was either that or she would be thrown off my lap. This also meant the soft fullness of her breasts was bouncing on my forearms. My forearms were rapidly becoming the second most sensitive part of my body. All I could do was hold on.
What I couldn't know was my grip on her waist was also pulling her cotton wrap tight over her bikini top and visibly stiff nipples. The friction on her sensitive nipples was making her horny. At the same time, my cock was being ground by her firm bum. As I was wearing speedos, the movement of her bum with every bump was gently unrolling them down my thighs.
By 20 minutes into our hour-long bus ride, my speedos were completely off my cock. This meant the cleft of her firm bum was being moved back and forth on top of my ever-ready cock. What was happening to us was hidden from view by her wrap and her bag sitting on her lap. Right now, the only thing between my rapidly hardening cock and her increasingly wet vagina was basically a piece of anal floss.
Looking back, I can't help but wonder how mom didn't notice. The only thing I can come up with was the potholes had claimed all of her attention. The idea of an accident must have so consumed her mind, she wasn't aware of externals. At least, that was I hoping! All it would take is one bad stretch of road and it wasn't long in appearing!
The bus, bad suspension and all, bounced through a deep pothole and the rear of the bus being lighter than the front, rose into the air. For a second or two, everyone was in mid-air crying out in delight or surprise.
Mum left my lap bringing my arms to their full length, freeing my rigid cock to spring up and when gravity returned, her sopping wet pussy came right down on top of it. It was over before we knew it!
Unsurprisingly, she stiffened at the unexpected intrusion. This was precisely the wrong thing to do! My inexperienced cock was now inside a seductively warm wet sleeve which had snapped shut like a rippling, flexible vice. I was barely able to stifle a moan at how good it felt.
Flushing under her tan, mum had felt what was happening under her, how could she not? But what could be done about it? There was no way to undo it without somebody noticing.
She was staring at two rows of double seats full of people who would make our holiday a living Hell through gossip! Most of them shared our hotel, but worst of all, they were turned in their seats to chat. We were caught.
Three seats away were Laura and James Gardener, a couple we had met at dinner the previous evening. They were laughing and joking with another couple she didn't know. The Gardeners were well aware of who we were and there was no way to explain this away. Thankfully, no one seemed to have realised.
Annoyed at her lack of options, mum leaned back to speak to me. Yet, before she could say a thing, the bus hit another bad patch. Not just one pothole this time, but a series of them.
Since I was securely seatbelted and the only thing holding mum down was still my arms wrapped around her waist. I could do nothing to stop her rapidly bouncing on my rigid cock for what felt like minutes.
When it ended, to her utter shock, she was taken by a fierce orgasm. It took all her willpower not to cry out at the sheer intensity of it. Gritting her teeth, holding on to me was all she could do.