"Bob La Londe" wrote

Well, in that case how about vinegar soda bombs. Hard to nail the timing
exactly, but that's half the fun. All you need is baking soda, vinegar,
and two liter bottles.

When I was a kid, we used to take my friend's dad's bottle capper, and some
of his beer bottles, and put dry ice and water in them. We'd toss them out
in the field next to his house, a grassy area. Sometimes they would blow up
on their own after a time. Then we'd go out with our bb guns and pop the
rest. I'm sure glad we never had one go off in our hands. We were luckily
stupid.

Steve