When you look left and Bruce Willis snaps your neck

Can be used in relation to anything involving distraction and misdirection by which you get everyone to look one way, while whatever you're doing involves going the other way.

As taken from Wikipedia, and which I checked out elsewhere, the first instance of this term is the title of a Jazz song from 1926 by Bennie Moten. Beyond that, it's a term that's only been given real meaning by the movie Lucky Number Slevin, in which it's used to refer to a kind of con game. Specifically a con in which a combination of distraction and subterfuge cause the mark to turn their attention away from the plot which proceeds in the opposite direction. The term itself is weighted with football, gambling, and other innuendo but since it didn't exist as a phrase until that movie was released, you could read that subtext into it or not. At it's simplest, a good head fake in sports is a Kansas City Shuffle. At a more complex level an army massing battalions of tanks on one front to occupy enemy attention and draw them out of fortified positions while in reality a naval attack ensues instead would also be a Kansas City Shuffle. In short, it's a cute name for a kind of misdirection.

From Lucky Number Slevin. The Kansas City Shuffle is a deception move characterised by causing the victim to look right as you attack on the left.