This was about ten years ago and i was at the airport departure gate, already queuing up get onto the plane. This young guy, early 20s, arrived at the departure gate while the queue was getting near its end but, even so, he started heading towards the toilets. But before he got there they put over one of those 'final call' announcements and, even though there is always still a bit of time after that, it obviously made him rethink his decision to go to the toilet and so he joined the queue instead. He was a few people behind me at this stage but I could already notice some of those telltale signs of his need to pee, mainly just through a bit more shifting about than you would normally do standing in line. He was in a grey suit, quite snugly fitting a very fit and slim body. The pants were tight enough to even show the outline of his briefs underneath sometimes, when he was in the right position or when his hands were in his pockets, because that would just stretch the fabric of the suit even more. In fact, his hands were in the pocket a fair but - but again nothing that anyone would have noticed who wasn't looking for it, as I was

Anyway, we got onto the plane and, amazingly, he had the seat next to me. He had the window seat in a row of three, and I was in the middle, with another guy on the aisle.
Of course, there is a fair time between the plain filling up with its passengers and taking off, and even more time before the seatbelt signs are turned off, so he just had to bear with the situation at that stage - but the shifting of his legs and the occasional clutching of his crotch (which itself was very well packaged!) was really drawing my attention.
But the most incredible thing of all was that when the seatbelt sign was turned off after the plane took off, he didn't get up to go to the toilet. I knew he needed to - not just by what i could see but by the fact that he had tried to go before getting on the plane, which was now probably half an hour ago. I think maybe he was just embarrassed to climb over two people, and we all know how difficult that can be with planes as crowded as they were.
But he did put down the table and that certainly hid things from anyone walking past - from everyone really, except me. For reasons I can't imagine, he then ordered a beer - he surely would have known this would have only intensified the situation. Maybe he just thought it would calm him down, or maybe it was just that young man love of beer that takes precedence over everything, and he just didn't give thought to the consequences. It was only a short flight anyway (50 mins). But his desperation was clearly getting stronger and more severe as his legs moved more and more often, and faster, under the table top, while he was drinking the beer, or when he would try to stretch but there was so little space to do that.
His hand was resting on his crotch much more often now and sometimes fully clutching himself, now on the outside rather than through the pocket (which wasn't really possible in the cramped seat of the plane).
I started just chatting to him about nothing in particular - where he was going, the flight - but he had a lot of trouble concentrating, and i have come to recognise that desperation in a guy's voice. It was all the sort of thing I loved so much because it was all so unstated.
Then when the flight attendants came and took the cups and drinks, etc,he handed over his beer bottle. Then they immediately then put over the announcement that we were about to land soon and for everyone to put up their table. That's when i did notice him looking around for the toilets but, as soon as he began to undo his seatbelt, the fasten seatbelt sign came on because we were close to landing.
He was really pretty uncomfortable now and I think that could only have been intensified by knowing that he had no choice at all but to wait. He was trying not to squirm, but he couldn't avoid it a lot more than he would have wanted and his hand was now permanently over his crotch, with more and more frequent grabs.
It was all amazing to watch but the last sign, just after we landed and started to disembark, was seeing him get up from the seat when I did, there was a very small wet spot on his grey suit pants' crotch. I don't think he knew it was visible because his hand was by now was moving back into his pocket, clutching himself from there. I can only imagine how much more had leaked into his briefs.
There were a few other times his desperation would show as we were standing and queuing to get off the plane: his toes wriggling through his soft-topped business shoes, looking out the windows in an attempt to distract himself when there was nothing to look out at, that sort of thing.
I made no mention of this to him at all and was just a bit ahead of him as we got off the plane and so could go straight to the toilet myself without it looking too much like I was going to follow him there. I went to the urinal but, unfortunately, he went to the stall. You can imagine how full-on that sound was and I have still often wondered what it was like for him, undoing his belt and suit pants at last, his briefs slightly wet.
That has been one of the lingering sightings for me!