To grow...

Your hands hold her hips as your rhythm gets faster, she's pressing her hands against the cubicle door and isn't even trying to stifle her cries as your full length sinks into her over and over again. You can feel that urge, she's so tight and wet and you want to hear her scream your name...

Your big, thick cock swells an inch bigger, half an inch thicker. Her cries get louder as everything feels tighter

"Fuck yes! Fill my tight pussy up with that huge cock!" She yells as you grow, several excited whispers outside tell you that you have an audience.

Amy's pussy feels like it's trying to **** you but you love it as that feeling of power flows through you. Your muscles swell and your clothes get tighter as you fuck her harder. "Fuck, I'm coming!" She cries out as you feel her pussy spasming around your cock as you wrap your arms around her and she collapses back against you causing you both to sit down hard on the toilet lid.

"Fuck me, that's a big cock..." She gasps as you reach forward and play with her clit, eliciting a groan as you do.

"Do you like them big?" You whisper in her ear

Looking over her shoulder seductively, Amy whispers back "the bigger the better"

You can't shy away from a challenge like that. Immediately you let yourself grow another inch longer, another half an inch bigger. You feel the back of her pussy being driven up from you as she screams your name and grips your wrist hard. You desperately rub her as she does and with another spasm she comes hard all over your cock.

"Holy fuck! What the fuck was that?!" Amy cries as her legs shake and her cum flows freely over your balls.

"About 9 inches" You estimate with a laugh.

Amy shudders again in your arms at this "Fuck me, I don't know how you did it. But I want more and I won't stop until you fucking fill me up with those huge balls."

With that she shakily stands up pulling your thick cock free and showing your handiwork. It looks massive, wet and downright dangerous as her small hand grips it, barely coming close to reaching her fingers and thumb together. The desperation across her face is plain as she straddles you and quickly lowers her pussy back down onto your huge length.