Go to the airport runway in a fast car (Infernus, Super GT, police cruiser, etc.). There are small yellow ramps scattered in the grass by the runway. Locate one, drive back a good distance, then at full speed hit the ramp so that only half your car actually hits the ramp. You should get enough spins to get the achievement.

Go on the Algonquin Bridge that connects Dukes to Algonquin. Find the part where the lanes split at the bridge when going westbound. At the split is a small ramp. Hit that ramp at high speed to make your car roll over several times. Try to land in the lower area for more room to roll over.