“He put his arm around my waist” – phone app submission

The other day I was along around with my friend. We’re both teenage girls and we were mid-conversation in a large space that was crowded but not immediately around us. All of a sudden a guy walks up right next to me from behind, put his arm around my waist, pulled me CLOSER and said “Excuse me” then walked off. It was incredibly horrifying/upsetting for several reasons.