An "Eselsohr" or "donkey's ear" is used to describe the corner of a page that has been folded inwards, resembling the floppy triangular ear of a donkey. "Eselsohren" occur in two classic ways: Unfortunate people who don't have a bookmark at hand might fold over one or more pages to mark their place, while slapdash readers might simply lean on a book and unthinkingly make a mess of the corners. In English people talk about "dog-ears" to describe this, but in Germany dogs have very tidy, pointy ears -- though you can't say the same for those unkempt donkeys!