He really did only have himself to blame, but he was more than happy to be blamed for it if he was going to get this kind of attention. All of his usual bravado was ripped away by Sam's hands and he didn't care one bit about his pride, his embarrassment over it all, or the fact that he was clinging to Sam. He wanted to be the one focusing all his attention on Sam, because instinct told him to, but he was more than ecstatic to be showered in attention. The kiss being so rough and messy was just an added bonus.
It was actually weird to be the one being kissed and touched when he was usually the one doing it, but this was incredible and he would just pay Sam back for it later.
Watching Sam slick his cock up, and shifting a bit at the feeling of having no fingers inside him, Dean reached down, hand curling around Sam's dick, stroking along it. "You're a big boy, huh?" His tone was full of playfulness and Dean pushed Sam back firmly after a moment, shifting forward to lean down between Sam's legs. Taking a breath for courage, ignoring the weird taste of the lotion, he took the head of Sam's cock into his mouth, sucking on it firmly.