Cas being basically the ultimate virgin was a good thing, Dean figured. One, he'd never had his cock sucked before, so there was no standard to compare it to. No pressure. Also, it set the bar really low. Dean remembered the first time he'd gotten his cock sucked. He'd come in like five seconds and the girl who'd been doing it spit it out all over his dick. It was messy. And kinda disgusting. And the hottest thing he'd ever seen.
...he had to admire the angel's stamina, at this point.