Doctor

 ... the Doctor costume." you said as the store attendant handed you the doctor costume package.

"I think I'll get the matching nurse one too." Said you girlfriend. You then proceed to checkout, and drive home.

At home you unpack the whole costume to find your costume was very good quality, it was a complete package with a short, black pants, doctor's coat, even a stethoscope for props, and for your girlfriend's costume were a revealing nurse outfit, complete with a head accessory. 

While your girlfriend was in the shower, and you were waiting for her you went thru her costume as you grabbed the headband that looks like a nurse hat and put it on your head.

Immediately you felt tingle rushing down from your head to your toes, as you watched you body shifted. Long blonde hair falls from your head, as your chest inflates, hips widen, and you feel an emptiness in your crotch area. 

Your girlfriend were shocked when she walked out of the bathroom to see a blonde girl were sitting on the bed. 

"Who are you?" she shrieked as you tried to calm her down and convince her that you were his boyfriend. 

"I think this costume has magical power..." you said while taking off your shirt revealing your developed breasts. Your girlfriend watched in awe looing at what used to be her muscular boyfriend now a curvy girl. You then grabbed the stethoscope and wrapped it around her neck, and in an instant her body grew taller, her hair shorten, her chest flatten, as her figure turned into a more masculine form.

"Holy shit! I got a dick!" she said watching her vagina slowly getting replaced with a hard erected cock. You felt funny inside, looking at her new masculine figure especially her erected cock made your new pussy felt damp. You walked slowly towards her, twirling your hair.

"I don't know what's wrong with me, but I'm feeling super attracted to you." you said biting your lips

"Well, having  dick and looking at my turned boyfriend really turned me on too!" said your girlfriend pushing you to the bed and slowly slide her cock in side your wet pussy.

You can feel your breasts jiggles with every thrust, the new senation that send waves of pleasure overwhelmed you. Both of you can agree that it was the best sex you two ever experience. And after experiencing multiple orgasms as a girl, and she has loaded so many cums in you, she collapsed as you both panting and giggled to each other.

"I think we're late to the party.." you said between your breath

"I don't care about that party now, i just want to spend the night with my girlfriend." he said as you cuddled into his arm.