driving finger 

Your middle finger. Usually refers to the one on the left hand so it can be displayed out the driver's side window to comment on another driver's behavior.

Your driving finger is the longest finger.

driving finger by andrew macnamee November 29, 2007

driving finger 

Another name for the middle finger. The name comes from the angry drivers who flip people off on the road whether it's from them cutting them off, running a red light or they just like to flip them off just to see what would happen

Some dumbass driver cut Leah off and ran a red light so Leah gave him the driving finger

driving finger by Suckin' on the Dictionary October 5, 2017

driving finger 

As opposed to the previous entry, this involves actually using a single finger to control the wheel, while you have the cell phone in the palm of your hand, and the other hand is either texting or dialing-- or seaching for the next song to play on the Ipod.

Johnny was using his driving finger to slip through traffic effortlessly, as he texted love notes constantly to his slut du jour.

driving finger by politicalsanity October 10, 2008