Usually only happens in a car with a manual transmission- A money shift is an accidental, far too aggressive down-shift, in which the engine performs the biggest red-line you've ever seen. It's referred to as a money shift, because it usually results in money coming out of your pocket for a new head, pistons etc.
My buddy Erin was doin around 65 mph when he accidentally hit second gear, money shifting his way to a new engine.
when shifting from 3rd gear to 4th gear and messing up and slipping it into 2nd.
I let my girlfriend drive my car but instead of backhanding it into 4th, she money shifted it and i had to backhand her.