Make her wear a ballgag here and now.

You reach for her backpack and open it. She does not stop you. You start taking out the ballgags one by one, placing them on the bed. For the first time, you examine them closely. They come in all sorts of colours, black, red, white, pink... There are also very different types. There's a plain and simple one, there's one with an extra strap for the chin, and there are even a few harness gags which cover the whole head in straps. There are gags with holes and those without holes. Small ones and bigger ones. There's even a ring gag and a bit gang in the shape of a bone, you belatedly realize.

19 gags. Basically every variation you could think of.

"I will choose one, and you will put it on", you declare. It's not a question. It's not a request. It's a statement. She knows it, and she doesn't protest. Maybe because she's still intimidated. Or maybe, because the situation starts, secretly, to arouse her. You're sure she would never admit it, though. You don't care.

You choose one.