To raise the index finger to in order to show that you are angry, pissed, annoyed or otherwise cross with someone. It is also called "flipping someone off".
Person 1: The psychiatrist told me that I had Oppositional Defiance Disorder because I did not want to take the over-prescribed drug for being "over-active".

Person 2: Dude, are you going to let that guy give you the middle finger?! (NOTE: figurative use)
by Moises (Moses) January 14, 2012
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