you sighed and said "Geese, if you're going to act like that I'd rather you'd have just turned me into a girl..." the orb glowed and you started to feel your body shrink in certain ways and expand in others.
"Just desire it and so it shall be." the orb explained as a lovely pair of breasts grew out from your chest
"I didn't even say I wish!" you complained
your girlfriend grinned and said "But you are turning into quite the cutie." as your hair lengthened to your back, and your hips widened. "...however I'd prefer it if you were a blonde." at which point the long hair in your vision changed to a nice golden blonde.
"Would you two stop messing with my body!?!" you screamed in your new feminine voice, and your body stopped shifting. Examining yourself a little you guessed that your breasts may be... E-cups? or did they just seem bigger since they were attached to you... You seemed to for sure be female all the way. You took a few deep breathes to try to calm down.
your girlfriend said "Sorry... I got a little carried away."
you cleared your throat and said "Well then orb. I Wish I was a man again." there was a silence where nothing happened. "Um orb? I WISH I was a MAN again!" more silence "The heck?!?"
The orb said "You wished I would stop messing with your body. I granted your wish so I won't mess with your body anymore." of course that was a very genie like interpretation of the wish, and the orb knew it. The spirit inside could just revert you, but it wanted to have a little fun at your expense... Although since it was a mythical being who knows how old it's definition of "little fun" could be very different than that of a normal human's. This left you shocked for a bit.
Your girlfriend gave you a slight hug from behind and asked "You ok?" in response