There was a new girl in class back in high school. We actually hit it off pretty well (definitely platonic). Well one day I'm scrolling through the sex offender registry to see if I recognized any in the area.
I hear: "what are you doing?!"
Right as I told her, I noticed a guy with her last name. I laughed and said "hey--he has your last name!" Her face got beet red and she ran out of the classroom.
Long story short, I got called into the office where the guidance counselor relayed that the person I saw was her dad and that she is glad that it was me who saw of all people and she trusted me to know it.