History of the middle finger

Before the Battle of Agincourt in 1415, the French, anticipating
victory over the English, proposed to cut off the middle finger
of all captured English soldiers. Without the middle finger it
would be impossible to draw the renowned English longbow and
therefore they would be incapable of fighting in the future.
This famous weapon was made of the native English Yew tree, and
the act of drawing the longbow was known as "plucking the yew"
(or "pluck yew").
Much to the bewilderment of the French, the English won a major
upset and began mocking the French by waving their middle
fingers at the defeated French, saying, "See, we can still pluck
yew! "PLUCK YEW!" Since 'pluck yew' is rather difficult to say,
the difficult consonant cluster at the beginning has gradually
changed to a labiodentals fricative 'F', and thus the words
often used in conjunction with the one-finger-salute! It is also
because of the pheasant feathers on the arrows used with the
longbow that the symbolic gesture is known as "giving the bird."
And yew thought yew knew everything.