Here recently I have received numerous FWD'd emails warning about a plastic bottle that you may find laying in your yard as just a discarded plastic bottle.
The email goes on to say that pranksters, practical jokers, someone seeking revenge etc. are making bombs from chemicals in the plastic bottle that when moved will explode with the force to remove fingers if you're holding the "bottle bomb" the worst part is that it takes a few seconds to explode after being disturbed. According to snopes.com the "bottle bomb" email is in fact true.
I was going to publish the email as an FYI but I decided to just explain this warning and warn that it is indeed true. The reason that I decided not to publish the email is because the email that everyone is forwarding explains in detail not only what this "bottle bomb" is and does, the email also explains what the bottle contains IE: directions on how to make the "bottle bomb"
So if you happen to find a plastic bottle laying around that has a liquid still in the bottle please be cautious of it, if you suspect that you have found a "bottle bomb" call the proper authorities, don't touch it. Better safe than sorry.
Below is a video of this "bottle bomb" in action and the reason I didn't publish the email that explains how it's made.