I've kind of wondered about the wisdom of doing something like that in a rural area where people may have guns on them or in a truck or something. I've always assumed that the photographer was in on it. It would be better if they weren't, but it seems like you're taking a chance on getting plugged.
Same deal with those people who do the zombie pranks and stuff. It doesn't seem like a good risk/reward ratio.
The dog in the tarantula costume may be worth the risk, though. The prank isn't that great, but the dog is hilarious.
How do you get the dog to cooperate? Very awesome prank