Hold that finger

Well, I assumed it's because that's the finger you start with when fooling around

Isn’t it because it looks like a dick n balls?

Actually it's a taunt as it's the finger you use for archery, and if you had your middlefinger removed you were deemed useless as archer. So those with middle fingers were showing off their mad skillzz

Oh kids... one sec... youtube: Robert Wuhl explains pluck yew.

I don't remember what country but I remember hearing that left4Dead had to change one of the game covers because showing the back of the hand was considered offensive (or something)

Shakespeare iirc?