This isn’t exactly harmless, got this from a friend a few years ago; kids were doing it...
Kids are putting Drano, tin foil, and a little water in soda bottles
and capping it up - leaving it on lawns. When you go to pick up the trash,
and the bottle is shaken just a little - in about 30 seconds or less it
builds up a gas and explodes with enough force to remove some of your
extremities. The liquid that comes out is boiling hot as well.
Don’t pick up any plastic bottles that may be lying in your yards or
in the gutter, etc. Pay attention to this. A plastic bottle with a cap. A
little Drano. A little water. A small piece of foil.. Disturb it by
moving it; and BOOM!! No fingers left and other serious effects to your
face, eyes, etc.
People are finding these “bombs” in mailboxes and in their yards,
just waiting for you to pick it up intending to put it in the trash. But,
you’ll never make it!!! It takes about 30 seconds to blow after you move the
thing.
See “SNOPES” below — it’s true — the video at SNOPES shows the
Indiana State Police Bomb Squad detonating one — it’s truly horrifying!
..... .. I checked “Truth or Fiction” and “they” agree this is TRUTH!!! So
be warned and beware.
http://www.snopes.com/crime/warnings/bottlebomb.asp
The scnerio you used is one that someone would do to be meanspirited or cruel. I doubt that what these kids set out to do.
The story doesn’t say what they used to pressurize the bottle, so I doubt that it was truly ‘caustic’. That word was used because if they said what was really used most people would laugh at the police.