Sam honest to god giggling was one of Dean's favorite sounds. Not that he'd actually admit that, of course, but he knew just what buttons to push to make it happen. Had them mastered.
Step one. "Sammy." Kick Sam's feet apart. Step in between them.
Sam would blush. Take a step back, bump against whatever was behind him - in this case, the washer. "Dean."
Step two. Lean in a little closer. Barely kiss his cheek. Not his neck, nothing sexual. Not yet. Just intimate. Sweet, much as Dean hated to think of it that way.
That'd make Sam close his eyes, keep looking down when he opened them. A smile would start tugging at the corners of his mouth.
Step three. Smile back, make sure Sam could see, even without directly looking. Then start unbuttoning his shirt, which worked out even better in this situation than most. "Here, lemme help ya. Prob'ly need to wash this, right?"
Sam would scoff and give Dean a nod - just a small one. Didn't matter what line Dean used to excuse undressing him. "Right. Yeah."
Step four. Start undressing himself, too. Didn't matter what he took off. In this case, he started by unbuckling his belt. "'N I should wash my pants."
And there. There it was. As Dean leaned in for step five, kissing Sam, the giggles erupted against his lips, Sam's fingers tangling in his hair.
Dean's matching chuckle was low, almost gravelly, and the sounds complemented each other nearly too well. Only after a full thirty seconds or so of kissing did Sam's laugh dilute itself into small, breathy sounds. "De."
"Sammy."
"We..." Sam's hand settled itself briefly against Dean's chest, holding him back, if just barely. "We should put our clothes in."
Dean did kiss his neck now, just behind his ear so he'd be close enough to whisper, "What's the rush?" "Can't fuck me on the washer 'till the lid's closed." Well, hell. Looked like Sam could push a few buttons himself. Dean didn't realize for about a minute that the moan he heard, way too high and way too close to a whimper, had come out of his own mouth.