A type of
firework. Basically, a shock-sensitive
explosive is wrapped tightly in paper. When thrown against a hard surface, it explodes, making a loud snap sound.
They are so named because you "whip" them to the ground and then they go "SNAP"!
Whippersnappers allow for great pranks. Placing them in unusual locations, such as door-jambs, on the floor near an entranceway, and nestled in the chain of a bicycle always make for fun surprises. You can also tape one to the bottom of someone's shoe when they're not paying attention.. The minute they get up.. *SNAP!*
I know someone who, on a dare, exploded one between his teeth. He said it stung like hell and left an annoying taste in his mouth for a while. I don't recommend you try it, though, as you may not be as lucky.