I caught my sister having sex and the image

I think a lot of my home, but my sister and her boyfriend, she thinks it's a big joke, having sex on a couch to sit on, anyone not want to invite, but I think she was afraid of her naked body, my family was always has been one of the beautiful. I think we've always, want to mend my relationship with my sister. 

But I do not know how to pronounce things without losing my temper. From what you've said in terms of worrying about your sister, imagining what your boyfriend what happened was not sexy, funny and embarrassing, and in no way seem to think. It is worrying, but if you are, then you should talk to him about it. I'd be too embarrassed to come it probably because things up with your sister seems to be taking the lead. Why not talk about it to suggest a meeting place for a coffee? You can do it without shouting angry, tell him it's okay, but you can move it so you have to deal with both.