From the archives of the Leica Users Group, i found this gem of a post.....
In the days of Agincourt during the war between France and England, which was fought with bows and arrows, the English Archer with his longbow built out of yew was supreme. The art of archery was called Plucking the Yew. But the French had a cunning plan. They planned to cut of the middle digit off the right hand from captured English Archers so they could never again draw a bow (or pluck the yew).
This plan came to nothing so to taunt the French, the English Archers would raise their middle finger and shout "We can still pluck the yew".
Owing to distance and the wind and the language barrier the French thought the English were saying PLUCK YEW. The dimness of time, and American vulgarism, has since wrought havoc with this historical
There is a web site somewhere that explains all this.