He couldn't help it.
Roadhog KNEW things like this got him real good.
So why must the sod insist on it?
Junkrat was pushed up against a cold stone wall, Roadhog's massive hand pressed over his mouth (and therefore also over most of the rest of his face). He could just feel Hog's weight pressing against him lightly, and the latter kept glancing over his shoulder through the round black lenses of his mask, suspicious that they'd been followed.
They were hiding.
To be fair, this really didn't happen often. The fight had been going pretty well. Lots of good explosions, Rat was yelling, at least until their opponents called in backup. They were outnumbered, they both knew that. And usually, that meant scarpering after tossing every last possible grenade and bomb at once. They fled the scene in the resulting chaos, Rat pausing very briefly to set up a bear trap for good measure. They ran (or at least, hobbled and lumbered) for at least five minutes before winding up here, in a dark side alley at the far end of Junkertown, breathless and high on adrenaline.
Junkrat had begun to speak loudly about how great the final explosion had been, but Roadhog still felt sufficiently in danger to stuff a hand over the little guy's mouth. So here they were.
There was a muffled voice. "You can let go now, ya big fucker, there's-"
"Shut up." Roadhog pressed Junkrat just a little further into the wall. There was a strangled whimper from under his hand and Rat went limp. The smaller junker could feel every crevice and bump that the wall had to offer, and it did nothing to help his hard-on, which was now straining against both his shorts and a vertical slab of concrete.
Like he said, he couldn't help it. Hog (cheeky bugger) KNEW this sort of thing set him off. It wasn't his fault he was hard as the wall he was shoved against.
Eventually, Hog noticed the quiet whining and Junkrat's failed attempts to move his good arm closer to his shorts, and lifted his hand. Rat breathed in deeply, panting slightly, cheeks flushed, and immediately turned his head to face his cohort. "Hoggieeeeeeeeee..." His facial expression said it all.
"..."
Roadhog didn't respond. Rat could almost feel the frown emanating from behind that mask. But he couldn't just shove him into a wall and practically crush him and not repay him in some way, right? He kept whining, kicking Hog's shins and struggling and generally making a complete nuisance of himself. "Tha's not fair, ya big cunt, you can't just-"
Roadhog had had enough. He turned Junkrat so they were facing each other and more suddenly than he'd anticipated, Rat found a hand around his neck, pinning him to the wall once more. "Ah, wh- aaAAHhhh..." Junkrat's initial question was overridden, because Roadhog's knee was now pressing into his crotch. Not hard enough to hurt, but enough. Rat gazed into eyes of the gas mask and saw something there. It looked like...amusement? Hog didn't ever really show any emotion aside from anger basically ever. Not that it mattered. Junkrat bucked against the pressure, gritting his teeth, eyes blazing as he tried his best to generate some sort of friction. Twitchy bastard. Roadhog just held him there, watching him passively, wondering if the little shit would just rut against him until he got off. He decided he'd better not wait to find out, and Junkrat's frustrated grunting was suddenly replaced by a shuddering moan as kneecap was replaced by a gigantic fist, shoving itself unceremoniously into his shorts and gripping his dick, hard.
"Ff-fuck..!" Rat cursed, screwing his eyes shut, squirming against Roadhog's steely hold. With one final check over his shoulder (just in case), Hog began pumping Rat's length, slowly at first, but swiftly building both speed and pressure until his moans were weak and raw, the hand around his throat tightening against vulnerable flesh, making him a drooling, light-headed mess.
He didn't last long. Less than a minute in, Junkrat came, spilling his load into Roadhog's palm, panting harshly and swearing and trying to remember how to breathe. Hog let go, and Junkrat snickered. "Ah, sorry, did I make a mess, mate?"
"..." With not many other alternatives, Roadhog wiped his hand on the wall, feigning disgust while Junkrat cackled his petty victory, re-buckled his shorts, and began leading the way back to their current hideout. "You know, mate, if I didn't know better I'd say you're almost as much of a kinky fucker as I am, right?"
Ten minutes later, a small group of men made their way down the alley, guns at the ready. They couldn't believe a pair that odd could escape them that easily; they'd scoured Junkertown top to bottom looking for those buggers, to no avail. One of them stopped, and pointed. The smear on the wall was milky white, and the same liquid stained the ground in a few places. "What the fuck...?"
They never did find Junkrat and Roadhog that day.