It's more an unofficially agreed upon position. There's always someone out there who most of the town has to agree manages a large degree of charm in spite of being a drunken lout who will clearly never amount to anything, and that's your town fool. Someone who will embarrass himself for the audience to have a good laugh, who plays a harmless prank here or there but only on people who needed to be taken down a peg, who has too much to drink in the tavern and stumbles home after dancing on a table, who never holds any one legitimate job for long...that sort of person.