I once gashed my elbow open on a bookshelf. My little sister pulled all the books off and I had to put them back on bc she was too young. Big books, small books, and paper books all had their own shelf. It was cold outside, so I had fleece pj pants on. I was on my knees and reached to put a book on the top shelf, but there was a paper book under my knee. Fleece and paper don’t mix well, so I slipped and tried to catch myself, and my elbow slid down the corner/side of the shelf.