Descente Dans La Folie
Find this one in the dummy town of Prosperity.
This one is fairly straight forward, but there are two sections where you'll have to drive up a rock wall to hit the marker. One is on checkpoint six.
The other is four checkpoints past the flaming jump. Don't fret too much if you miss that one- you have enough slack here to miss 2-3 checkpoints and still clear the stunt. Note that is entirely possible Tweak will run across the course as you make for the final checkpoint. Do not hesitate to run him down.
Reaching the final marker in time completes the stunt, and unlocks the Bailout truck.