Throughout all the courses, there are cones and signs. Basically, all up you need to hit them 100 times (not all in one event, or all the same cone).
On the Beginner course, there are five on the grass between the track and pit exit, just before turn 2. If you hit these well, you can bounce them onto the straight and rack up the hits. There are also five cones after turn 3, just before the pit entry and finish line - these are harder to exploit.
I suggest combining this with the "Karaoke Clear" achievement, as that mode allows you a free track and shots at the cones. However, any modes count towards this. The cones are also worth one second each in the Survival mode, so you may want to rack up some hits while going for "Survive: 5000".