Disign the great show

Think of what may Sarah do, Jon pleaded, "wait, please don't involve Karen with this! Please!"
Sarah looked at Jon for a while and smile with a grim on her face, "oh Jon boy, or maybe Jon girl, what make you think you can give me an order. But I am so kind that I would not use the stone on Karyn."
"really?" Jon was surprised at what Sarah said, "I appreaciate it very much."
"But you will." Claimed Sarah, "You will use the stone on Karyn yourself."
"What, no, I wouldn't, I" astonished John and Sarah makes her wish, "I wish I will be invisibile from the moment I leave this room till the moment I come back to this room again. I wish Jon will do the exact thing I discribed when I next give him the stong, first he will wish we both an Karyn's place, second he will make a very mischief wish on Karyn, and finally he will wish we two back to this room."
"no,no, i can't" Jon retreated but Sarah carried on, "and I wish Karyn will see Jon as his male form instead of current female form." Then Sarah step up to Jon and stuff the stone in Jon's hand.
"No," Jon try not take the stone but failed as he now is a girl and lost a lot of strength. Then he wished,"I wish we two are now right in front of Karyn."