What does this insanely awesome button do?

The 2014 Jeep Grand Cherokee SRT8 is home to perhaps one of the most appropriate buttons we've encountered in the What Does This Button Do? series. Mysterious buttons are rarely spelled out as clearly as the Jeep SRT8's, or as fun to use.

By spelled out, we mean the whole word, "Launch," appears on the button to designate the 470-horsepower, all-wheel-drive Jeep SRT8's Launch Mode. There are no acronyms or guessing with this button. What the button does is also made clearer by the awesome depiction of a drag strip's starting-line lights, aka a "Christmas tree."