You decide your first victim will be Chad, the football captain known around the school for his large penis. Sneaking into a bathroom, you make it so that he will have a 1 inch soft dick by the end if class, with you gaining all of the length, and much of the thickness.
As class starts, you feel it's magic working. Chad readjusts his package every now and then, while you have to start unbuckling your own pants to deal with the new pressure. Chad begins to freak out, and when class ends, he heads to the bathroom, and freaks out at the loss. You magically adjust your pants to fit your new dick, and it will continue to expand when you choose more men, this time being.....