Here's a sci-fi scenario I've thought about a lot:
Three guys are sent on an infiltration mission from space to a planet. Even before the briefing one of the guys mentioned he needed to visit the restroom, but the team is bustled onto the dropship before he can. It's a pretty long trip to the planet, at least a couple hours, and the dropship is only meant for these "short" jaunts to and from planetside so there's no facilities on board. The guy is absolutely bursting an hour in, but there's nothing he can do about it - and little does he know the second guy on the team is in the exact same boat. Guy 2 really wishes Guy 1 would stop squirming around so much, it's only reminding him of how badly he needs to go. But both of them have a bigger problem: Guy 3, who doesn't need to go at all and thinks this whole situation is hilarious. He keeps teasing Guy 1, bringing up water, asking if he's gonna make it, laughing at his situation. It makes it even harder for Guy 2 to admit he needs to go too, because then he'll be teased just as much.
Finally they make it to the planet, landing somewhere secluded, and the instant the doors are open Guy 1 runs out and pisses off the gangplank, not even waiting to get his feet on the ground. Guy 2 follows, trying to hide just how badly he needs this, but his hands are shaking as he gets his belt undone and Guy 3 catches on, teasing both of them mercilessly.
Now that the crisis is over though, both guys have no problem focusing on the mission. It takes a long time to complete, probably 4 to 6 hours, but they pull it off and - remembering their painful flight down, Guys 1 and 2 make sure to empty their bladders before getting back on board the dropship. Guy 3, however, hasn't gone all day, and tries to be nonchalant about the fact that he inevitably has to pee by now too. The other two guys, tired of his "jokes," sent him to prep the shop while they both went. Once they're on board he tries to excuse himself, but they ignore him and close the doors and tell him to strap in.
It's been at least eight hours since he peed, maybe longer. A couple more hours before they get to the main ship shouldn't be that bad, right?
The other two guys, of course, knew what they were doing all along. It's a dick move, sure, but they're not cruel enough to rub it in on the way back. They both pretend they haven't noticed how uncharacteristically quiet Guy 3 is during the flight. Or how tightly he starts gripping the armrests of his seat, or the pained gasps he makes when the ship goes through the atmosphere.
When they get to the main ship, however, they're all expected to report about their mission right away, no time to relax (or release). Guy 3 is in absolute agony the whole time, still trying to pretend he's fine and not seconds from exploding, well aware of how hypocritical it would be to complain or ask to be excused.
At last they finish their report, and Guy 3 desperately stumbles for the closest bathroom, Guys 1 and 2 following because hey, it's been a few hours now, might as well go before they head back to their quarters. And though they genuinely didn't mean for this to happen, they have a perfect front row view of Guy 3 losing control and flooding his pants, leaving a huge puddle on the floor just two steps from the bathroom door. He's clutching his crotch and trying to stop it the whole time, soaking his hands and sleeves too, honestly kind of impressing the other guys with how much he'd been keeping inside all this time. But they still can't help themselves from calmly walking past him as he stands there, piss dripping from his clothes, horrifyingly aware of the fact the two guys he'd teased for needing to go at all just saw him fail to hold in his pee.