This one will come eventually through regular play but if you have 2 controllers, you can grab it pretty easy on your own.
Go to split-screen and load up any arena. Cycle through power-ups until you score the Scorpion (it's the one with a single missile icon). Position your second controller about 100m away facing your main vehicle.
When you have both cars facing each other, hold down A on your second controller. When you have a missile lock with your first controller, fire the Scorpion and when it is close to striking, release A. If you time it properly, the second car should flip into the air as it gets hit by the Scorpion and achievement should pop.