Looks like the same things I take out of spray paint cans to shoot out of slingshots sometimes. I'm sure everyone of us as taken the "noisy things" out of the cans to find out what they were when kids, or was that just me?
hew: I've been playing around with Kleenex in my BG too! I was trying the "Grasshopper Shot/Load" (I think that's what the guy called it) out. I forgot where he posted it at, but he uses it to shoot grasshoppers and spiders. Here's a video for anyone who has not seen it and is interested.