Your sister Tina (18) going on toilet

You see Tina going to the toilet. She has a beautiful face and long brown hair like Kim. She had a nice little ass, that was still in good shape, and B-cup boobs. She was wearing a black skirt and a T-shirt.

You see her pulling down her skirt and her panties that you can see her pussy and her brown bush. She sits down on the toilet and you hear the pee going out of her bladder.

Do you wait until she's gone? Do you head to possess her or a body part / object of her? Do you try to leave now? Or do you stay where you are?