Randy: You can paint a big fake train tunnel on the rock outside of town... maybe coyotes will run into it.
Darnell: Or maybe road runners.
This is a reference to the Looney Tunes cartoons starring Wile E. Coyote and The Road Runner. Wile E. Coyote would pull outlandish stunts in his attempts to stop or capture The Road Runner including painting fake openings on large rocks or canyon walls. The two had become popular enough to earn their own series called "The Road Runner Show".