"You know that your BF has a huge boobs and breast expansion fetish. You want to please him so you buy some magic balloons that will give him everything that he wants. The magic of the balloons is so powerful that they will make you grow according to how much the balloon is blown up. The bigger the balloon gets, the bigger you get."

Oh my, you have already got my tits tingling with growth just thinking about this hot request. But, you aren't going to make me too big, are you?