A button in a car, usually labeled 'overdrive' or 'sport mode,' that allows the driver to switch from regular driving settings to having the full output of the engine go straight to the transmission and tires. Higher RPMs and thus speed are a by-product. Mainly used when climbing up a hill so that the engine doesn't struggle too much in a lower gear, or when quickly passing another vehicle on the road.
Dude, my Volvo is sick! It has seat treats AND a fun button!