College students have loved beer for centuries. They are also generally very smart. In one fit of brilliance, students invented biernagels (beer-nails).
These are metal studs placed on the covers of books to keep the
leather covers away from wet (spilled beer) pub tables. With
biernagels on it, a book cover is raised half a centimeter from
the surface of the table, and thus remains mostly dry. From
the name, we can only assume it was some inventive German