Jeff tried to push himself away from his father's hairy ass, but when he lifted his arms he found that he wasn't lifting anything at all. His arms had merged into his torso and was looking particularly shiny. He was only 18 inches tall now and discovering that his father wasn't particularly thorough about cleaning his backdoor. This was discovered by his tiny head being rubbed rather forcefully along the hairy crack.
Despite Mike's belief, instilled by the Chronivac, that this was a routine punishment, this was the first time he had played with his ass and the first time he was discovering how sensitive he was back there. This was why the Chronivac had picked this form for Jeff as the thing Mike truly needed. Mike let out a slow groan and pressed Jeff a little harder, his hairy hole resisting being penetrated but still gripping his shrinking son's face.
Jeff let out a little whimper, "You don't have to do this, Dad. I'll be good." The only part of him recognizable as anything another than a particularly large blue silicone dildo with hefty balls was the part hidden between his father's cheeks, because his human face was at the end of the dildo.
Mike's hole swallowed at that promise, and his son slid in a few inches, far faster than he planned. Jeff may have been under a foot but he was still very large for a newbie and not getting any smaller. "Jeff, you're always good for a few days after a good punishment." It was dark and humid inside his father and the fact that his dad wouldn't stop groaning and whimpering with every little move he made with Jeff had the young man feeling some kind of way.
It wasn't long before Jeff found his face pressed against a bit of the muscular wall that was just a bit firmer than the rest that was constricted around his body. When he headbutted it, his father cried out, not in pain but in a kind of ecstasy he had never heard, even when he'd 'accidentally' heard his parents together. Mike gripped his son's base and Jeff felt like there were two hands on his firm young butt. Then the young boy was being jack-rabbited against his father's prostate, he face squished on every thrust that had his father gasping quickly, almost hyperventilating. Jeff felt his nuts crash into his father's as he was pressed all the way in and the walls close in tighter around him. His father was cumming, and all over his sheets too.
Not that Jeff would be finding that out right now, Mike pulled his briefs back up, leaving his son buried deep inside him for the rest of his punishment.