OK, here's what you do. You just sneak up in front of 'em, and then honk. And they do the rest. Watch this.
9 seconds sound clip from the Cars movie soundboard.
You can hear this line at 00:54:53 in the Blu-ray version of the movie.
Quote context
[...]
- Come on. You'll love it! Tractor-tippin's fun.
- All right, listen. When I say go, we go. But don't let Frank catch you. Go!
- I swear, tractors is so dumb!
- I tell you what, buddy, it don't get much better than this.
- Yep, you're livin' the dream, Mater boy.
[...]