Jeff picked his mind to no end, but he couldn't really think of anything creative after sitting and thinking for a while - so he decided he would go down the list of options provided by the Chronivac, starting with the first option - swapping his arms with his legs.
Apparently, the Chronivac had the transplant option preset. A small screen popped up on his computer: Perception of Reality? (Yes: Transformee either knows that they have been changed or No: thinks that they have always been what they are) - He had to backtrack and fiddle with the selections a bit more before finalizing the transplant. If he was going to try out these changes, he obviously wanted to remember that he had changed himself, but wanted everyone else around him to believe that he had always been that way and nothing was out of the ordinary. That way, he could go out and see what people did or said when they saw him.
He confirmed the change, and waited. A few seconds later, he felt the bizarre feeling that he was being pulled like taffy. It was clear - He knew the change was actually happening and he immediately got excited! Looking at his arms, they were getting larger and a bit less muscular - and his hands were losing dexterity. Jeff often worked out at the gym down the street, but although he did a lot of weightlifting, he wasn't one to run on the treadmills or use the step machine, so his legs weren't as toned as his arms. He was impressed to see that his hands were turning into feet, all the while he felt the almost exact opposite thing happening with his legs. His big toe was moving away, separating from the rest of his toes and looking more and more like a thumb by the minute. The chronivac must have considered his feet and hands to be a part of the swap, as they were attached to his legs and arms respectively.
His elbows rotated backward and broadened out - turning into knees that worked similarly to his elbows but faced backward, in the direction he was facing. He marveled at the fact that it looked so natural as well, that the legs looked like they belonged joined at his shoulders, which now more resembled hip bones.
When it was all over, Jeff stood up to take a look at himself in the mirror, but his new legs (which were now his arms) couldn't support his weight and he fell to the floor. "Well this sucks," he thought.
Strangely, though, he naturally got up using his feet and legs (which were now his arms) without really giving it a second thought - even though he knew it wasn't normal. And it worked! He was naturally standing like he always could, but upside-down! He was hand-standing with his feet! "Awesome!" he shouted. His head now had to crane up to get a good look at himself, since it was closer to the floor between his legs now were. But he could move his arms about - still fully functional - and grab things with his swapped hands. It's just that they were way above his head and he had a bit of trouble seeing without looking in the mirror. With his clothing on, he really did look like a strange monster out of some crazed video game - it was really turning him on.
Now that he was a walking science experiment, Jeff wondered what he would do next...