Here's a demonstration common in chemistry classes. Two chemicals, hydrochloric acid and ammonia, are placed next to each other. They don't touch. But one suddenly starts smoking. What happened?
This video will let you see scientists do to a cheeseburger what Judge Doom did to that cartoon shoe in Who Framed Roger Rabbit. They dunk the cheeseburger in hydrochloric acid and see what happens. It's not an explosion, but it's a pretty good show all the same.
There are plenty of ways that pennies made before 1982 are superior to ones made afterwards: The pennies themselves are worth more, as they're made with solid copper. When flicked or dropped, they have a pleasing ring to them, while modern pennies thud. Finally, early pennies can be used in a bunch of fun science…