Drunk

So yesterday evening, my sister, a couple of friends and I all went out. We were drinking (all of us were legal) and some of us got a little bit too tipsy. All in all it was a really fun night. So we all went home (my sister was crashing on my couch). The next morning my neighbour came over and said, looking embarrassed af, I don't think this was meant for me. It was a picture of one of my friends lying on some guy butt naked. And this friend was not a slut, she rarely drank, and she has never had sex, or even a boyfriend. I don't know how to tell her. What should i do? (There was also another picture of her with a girl. They were both fully clothed but they were about to kiss. I don't know how tool the photos either!)