When I was a destructive pre-teen, my cousin and I would make ping-pong ball smoke bombs.
Take a ping-pong ball and gouge a small hole in it. Break the heads off of as many strike-anywhere matches as you have the patience for, and put them into the ball, along with a few pebbles for friction. Wrap the ball in masking tape, to taste. Hurl the ball high into the air in such a manner as to cause it to collide with a relatively hard surface as gravity causes it to return to the surface of the planet (or a reasonable facsimile). Watch the ball: A) begin to produce copious amounts of foul-smelling smoke, or; B) burst into flames -- either is entertaining enough to be worth the trouble. Repeat.
And, as a bonus, if you omit the step in which you wrap the ball in tape, you can actually watch the disintegration of the ball, a process which is both fascinating and difficult to describe.
Don't actually do this, of course, because it would be wrong.