You’ve probably done it thousands of times. You know, made an inappropriate joke about the plane going down and then touched wood just in case.
But why do we touch wood, or knock on wood, to ward off bad luck?
The phrase is relatively modern – the oldest citation for the British version of the phrase ‘touch wood’ dates from 1850, when it was used in the academic correspondence magazine Notes and Queries. This predates the American ‘knock on wood’ expression.
And there are a few theories as to how it came about.