courtesy wave 

After signalling, being given room to change, and changing lanes, a driver should wave, indicating 'thanks' for the room given.

I cut him off and gave a courtesy wave; he gave me the courtesy finger.

courtesy wave by Mike P. Grant, Esq. February 8, 2007

Courtesy dwi wave 

A wave similar to the courtesy wave, done while driving under the influence. This wave is often done with the hand that is holding the container of alcohol because the other hand is firmly holding the steering wheel.

Dude 1: "I heard you almost got in an accident last night."
Dude 2: "Yeah dude, we were so drunk! The dude that was driving cut off this van and almost ran into him! He stuck his beer can out and waved sorry to the guy though."
Dude 1: "At least he gave him a good courtesy dwi wave..."

Courtesy dwi wave by Da Vin Chee January 12, 2010