You decide to enhance something else

Stacey closes her eyes, waiting for you to write on her again, but you have another idea.

Stacey has already had fun messing with the size of her gals earlier and there was something you were curious about changing yourself. Something that nearly every guy in their life has thought about enhancing at one point or another. Hell, there was a whole online spam industry devoted to it.

So, while Stacey's eyes are shut you turn the pen in towards yourself and write (upside down) 10 INCH PENIS just above your stubbled pubis.

You grin as your slightly above average six inch cock grew down your leg, stopping just before it got to the knee.

"Holy sh-" You curse in amazement at your new appendage.

"Huh, have you done something yet?" Stacey opens an eye and peeks at what's taking you so long.