Schlitzohr

In medieval times, members of particular craft guilds were identified by rings in their ears. When someone fell out of favor with the guild, he wasn't just kicked out of the club, his earring was ripped from his ear. He was then left stigmatized with a telling scar. Nowadays, a "Schlitzohr," which literally translates to "slit ear," doesn't quite carry the same stigma. Rather, it can be used to describe just about any sly rogue or rascal, whether you'd expel them from your group or not.