Your hand slips and you accidentally hit the enter button. "Uh-Oh" you think. "I didn't want to become that body, I just wanted to see what it could do."
But the changes are already underway.
First your skin tone turns more dark and your eyes narrow. Your hair turns black, and your eyes brown.
"Hey! I'm still 18! Maybe it didn't work," you think.
But then all of a sudden your height drops, your muscles shrink, and your genitals become pre-pubescent again.
"Whoa! I'm thirteen again!" You think, but the changes aren't over yet.
You get a little taller, and gain more muscles. Your now loose shirt begins to stretch as your pecs and six pack begin to force their way out again. Then suddenly, you feel an intense tightening in your pants. Your crotch is getting MUCH bigger, bigger than it was when you were 18! It must be nearly 10 inces flaccid now! Your balls also get bigger, causing intense pain as your pants stretch to extreme limits. Your face becomes dotted with freckles, and buck teeth force their way out.
Then you suddenly learn many facts relating to martial arts and wrestling, and remember that you are a black belt. Then all of a sudden, you remember that you aren't doing well on tests, and school obviously is not you talent.
"Maybe I should, uhh, try again," you think, struggling with the difficulty.
"Or maybe I should just see what its like to be, uhh, in this body," you add, looking down stupidly at the gigantic bulge in your pants.