Language. Abstraction. Shape. Context. Arousal. The information that made up Jeff's memories flooded the donkey who had been so abruptly swapped into place, the experience of humanity overwhelming to the point of...
The donkey who was currently human Jeff came, spraying into a prepared tissue. Post-nut clarity came with a double-dose of existential horror: that wasn't an image editor, that was a real swap! And frankly, the donkey had no interest in going back!
Realizing that the original Jeff would suffer horribly left unattended from his own viewpoint, the donkey sprung into action figuring out what to do to fix this, checking menus and options and pointedly not changing anything just yet. Eventually, he found out that the Chronivac could copy Jeff's data to the donkey-body, turning him into a twin. Setting the distinct name 'Geoff' for himself and letting the original Jeff become Jeff, Geoff updated the transformations and...
The donkey in question popped into Jeff and Geoff's new room, followed by imploding into a naked and confused human Jeff original with suspiciously exact body match even for a twin.
"What just happened?" he said, suddenly getting slammed with memories of a twin brother.
"This isn't a photo editor, it's a reality editor!" Geoff explained while pulling up his pants, proceeding to make an 'auuuugh' noise that came out more as a bray (force of habit). "I'm not going back to being a donkey, so you're just gonna have to live with me for saving you from that."
Fetishes, trauma, and trying to juggle several faded memories of parallel histories zoomed through Geoff and Jeff's heads, before Geoff tentatively said "Let's...let's be a lot safer with any future changes. Don't do anything permanent that can't be undone, got it?"
"Got it." Jeff said, opting to scramble for the dresser to grab some replacement clothing. "That was...crazy close. Thanks for saving me back there, it was awful...it'd be something if it was temporary, but to be stuck like that? No way, not anymore. Fantasy only territory, that."
Geoff agreed, mostly because his preferences were basically Jeff's with a bit of leftover donkey habit and personality. "Totally. But uh...this is a pretty powerful machine. If we're gonna try it out, we could really do something. Maybe try centaurs next round so we don't have to worry about hands or separation? Look, I was a donkey until basically a few minutes ago and now I'm your twin brother. That's crazy. We're not crazy. Something's up, and this is worth investigating."
Geoff proceeded to actually flex and investigate the whole 'human hands' thing as more than automatic computer-use muscle memory, mildly in awe at the whole liftable-arms thing but not really.