Imagine this… you are driving up the road and you come around the corner to find a strange, unidentifiable object wedged into the ground with smoke and flames all around it. Would you believe that aliens have come to visit in an unexpected crash landing?
These motorists certainly fall for the set up, and I would likely be guilty of that too as I am somewhat gullible. Their reactions are hilarious as the fake cop walks up to the “flying” object with them and suddenly the hatch opens above the craft.
They probably could have come up with something a little more interesting, or even scary, to pop out of that hatch, but it is still a good practical joke, none the less.