I'm shocked that nobody has mentioned the gasoline in the glass bottle trick. I'm sure that many of you know what I'm talking about but for those of you who don't, here'* how to do it.
Take a glass bottle with a metal top. A screw-on top works best, but you can make do with a carefully removed crimped on type in a pinch. Punch a small hole in the cap, like 1/8-3/16", give or take. Fill the bottle about 1/2 way with gasoline. Put on the cap tightly. Carefully, and quickly, put the bottle in the hottest part of the fire that you can reach (it'* only arm hair, it grows back). Back away at least 5 feet. If all goes well, you don't need that space, but it doesn't always go well... Anyway, very soon gas vapor from the boiling fuel will shoot out of the hole in the cap, ignite, and shoot flames into the night sky. Near the end, the thing usually breaks and you get a nice mushroom of fire, size depending on how much was left in the bottle. It'* good fun. Far less messy than the can of peas in the fire, too.
Oh yeah... Kids: Don't do this at home without adult supervision.