The Chronivac was malfunctioning, even though no one was aware of it, so it wouldn't be a surprise that an ERROR message appeared on the screen just as all the changes made by Jeff suddenly reversed themselves.
One moment, hairy Jeff and muscular Derek were having incredible anal sex, then the next ... well, they were still having anal sex, but they were back to their original non-hairy and non-muscular straight selves.
"What the fuck?!" Derek yelled, his eyes nearly popping out of his head in shock and disgust, as he looked down at his cock embedded deep into Jeff's butt.