I flipped the finger at a driver who was deliberately blocking my right of way.  His shot shattered the back window of my car.  He was caught after hide and seek episodes.  Prosecutor called him a bad boy and negotiated a plea; guy got off real easy.  He knows my name and address which the prosecutor said were confidential. 

Agreed.  Flipping the finger can be life threatening, but I still do it.  Not habitual, but I do it. It might be a small way of telling folks I won't be intimidated.