If you go to your map(press select) and go to the upper-left hand corner, you will see an Empire Diner and a road leading down from it( it curves a little and is on the left side). To the left of this road are three gray "nubs" that kind of look like small fingers coming off the side. On the side of them closest to the Empire Diner, there is a large grassy area with trees on it. Drive here, and when you have speed built up, hold the emergency brake and tilt the left stick right and left quickly. This will take a few tries. You can also try to do it after not having much speed, like 20 mph and tilting the left stick side to side. You can also do this while trying to go in circles if you can't get it just going side to side. Remember that you have to be in a mission for the points to count.