Here's what you do. First, get a thick metal pipe just large enough to hold a bowling ball, about 8 feet long. Drill in a hole in the side of the pipe, near the backend, maybe .25" wide. Put a rope in it, covered in gunpowder. Fill the bottom with a couple pounds of gunpower or any explosive of your choice. Put the bowling ball in. Aim the pipe in the direction of the road, out of a window of your house. Wait for retards to come driving by, and light the fuse. Even if you don't hit them, you should scare the SHIT out of them, driving them off. Failing that, recalculate the trajectory.

Note: Do mind the recoil, yeah?