Well... Sam was far from quiet right now, what with the almost obscene slurping noises and gurgles as Dean's cock hit the back of his throat. His jaw ached, his neck was cricked and he was getting terrible cramp in his wrist. But the moans he was drawing from Dean made it more than worth it. The way Dean was coming undone under his ministrations, the writhing, the hair pulling, the weight of the world dissolving from his shoulders for just a little while - made it all so, so worth it.
He didn't slow down. If anything, Dean telling him he was close just egged him on. He fought against his gag reflex, letting Dean's cock slide into his throat just a little. It was strange, and kinda hot.