-A projectile (ex. baby carrot, airsoft BB)
-Something to shoot at (optional)
Step 1: Blow Up the Bag.
Step 2: Load the Projectile.
Step 3: Quickly Slam Your Hand Down on the Bag.
Step 4: Warning (common Sense)
1. Don't shoot it at your eyes or someone else's eyes.
2. Don't shoot it into your mouth or another person's mouth.
3. Be careful with sharp projectiles.
4. I can't think of anything else.
While it doesn't look dangerous, at short range a hard enough projectile can leave bruises (ex. carrot) (I'm sorry Jack). I hopefully won't be held accountable for any injuries or damages. Also, It really shouldn't take too long or too much effort to make. Most of all, though, have fun with this.