A variation on the "middle finger" obscene gesture. The wrist is cocked at a 90 degree angle and only the middle finger is extended straight in the air. Generally considered to be a more elegant way to express "<screw> you".
Steve and Mike gave Andy the Wallace Presentation when Andy asked them to pick up the tab.
A more elegant and dramatic version of giving "the bird" / middle finger. Possibly Scottish in origin. The wrist is cocked at a 90 degree angle, palm facing up, and the middle finger is raised straight in the air.
William showed those English bastards the Wallace Presentation at Stirling Bridge