YouTuber InfraBren went into a library and made some loud sex noises (while throwing his voice) to confuse, delight, and terrify everyone in the room.
This is truly the greatest mystery these people have ever encountered in a library. Excluding that time Encyclopedia Brown figured out the case of the Civil War sword. That was a mystery for the ages.
You can see two more “Sex Noises In A Library” videos here and here.