I try to never use “the finger” when another driver is being an ass. In that case I always just give them a thumbs down and a sad face.

I save the middke finger for people who are being “nice”, especially when it is making things dangerous. I find it is the quickest way get them to just go.

I try to be coniderate while driving, but I believe being predictable is safe. Deviating from the rules is dangerous.