Your girlfriend turns into your sister.

"Well, don't look! This needs to be a surprise!" Your girlfriend exclaims as she signs you to turn around.

You turn around slightly out of curiosity, but she catches you and screams "Hey! No peeking!", her voice slightly rising in pitch towards the end of the sentence.

You stare at the wall and count to 20, which you dare to assume is about the time it would take for someone to transform.

As you turn around your jaw drops to the floor: In front of you stands a carbon copy of your 18 year old bratty sister, a high-school senior and captain of the cheerleading squad, in a white tank top, and black skirt showing off her hourglass shape and pair of D-Cup breasts, along with a pair of sandals.

She doesn't even look up at you as she chews bubblegum and texts nimbly with her petite hands tipped with shining black nail polish, "Like, what do you need now, big bro? I'm, like, super busy".

After staring for a few seconds you manage to ask, "Is that still you in there, honey?".

She lifts her gaze only to roll her eyes at you while playing with her waist-long blonde hair, gathered in a ponytail, "Whatever. Did you, like, want this to be a role-play or not?". She was behaving exactly like your sister! How did she do that? She nailed everything from the mannerisms to the speech patterns as if she had known her for years! Yet, when looking into those ocean blue eyes you could somehow still tell it was her.

Noticing your shock and the growing bulge in your pants, she starts walking slowly towards you, gently grabbing you cock with a manicured hand, "Well? Are you going to, like, do anything with me or are you just gonna stand there like a total dweeb?"