You confront her

(Guys, feel free to follow along and become a premature ejaculator. May my sister be your guide into sexlessness)

She comes into the room, just a towel around her body. You feel awkward, but as her older brother you need to talk with her about this. She trusts you, and sexual perversion is a serious topic. You want her to have a healthy intimacy with a nice guy some day in the future. Like you have with your girlfriend.

You tell her to sit down, and then throw all kinds of generic phrases at her. About the dangers of pornography etc. She is upset that you invaded her privacy, but calms down as soon as you ask her, why she likes the kind of things you saw there.

She says: “Because..its the feeling of power. Being so sexy that a guy cant hold his orgasm, that he embarrasses himself, even though he tries not to. Don’t you think thats sexy?”

You: “Well..yeah i guess that can be intriguing, but..”

Sister: “Does it ever happen to you? With your GF?”