[mmercier]

Sometimes, when working around masons I will take an empty coke bottle and put in some muriatic acid. Then quickly put a foil from a gum wrapper and tightly close and toss the bottle.

Loads of fun. If you get it right it pops like a cherry bomb.

guess this makes me a nitwit too, but it is fun.

[HiTech RedNeck]

Where does the acid go when that happens? This sounds like a somewhat hazardous thing to try around biological entities.