I've read blogs like this on Reddit, and other sites. Where in the poster asks what is everyone's scariest experience

This will mainly relate to non-ghost experiences, as I am a skeptic. Stories of odd occurrences, weird meetings, creepy people, the only rule is that the story is true and about you or someone close to you. Stories similar to r/LetsNotMeet, or whatever.

A creepy experience to someone close to me, was at my school. My school is separated into three buildings, and academic, an art building(no lock on the door), and a more general fine arts building. Well, one day during an art class, a man walked up to the art building, and walked inside. He walked into the main classroom, and just took several pictures of the students, and the teachers. The man hadn't signed into the front office, as evident by his lack of a slip on his shirt, or at all. My art teacher walked up to him, and asked him if he was a student's parents. The guy told her he wasn't, and he walked back down the steps. My art teacher followed behind him to make sure he left, the guy walked out of the building, and got into his car. He drove off, and no one knew who the fuck he was, at all. Suffice it to say we got a lock after that.