The seventh

An English tourist is on holiday in a Cornish village when he spots what is obviously the village idiot sitting next to the horse trough. In his hand is an old stick, and tied to the end is a piece of string which is dangling in the water. The tourist decides to humour the fellow and asks, "Have you caught anything yet?" The village idiot looks up and studies the stranger before saying, "Aye, you be the seventh today."