A paper cracker is like firecrackers - it makes a loud noise (not as loud as firecrackers :p). The difference? You can make one with only a piece of paper!
Step 1: Materials
All you will need is:
-A sheet of lined paper
Yes, you heard me right. Only a sheet of paper. But for best sound (loud), then go with paper that's thinner than blank paper, since it needs to unfold really easily. Kind of like Magazine Paper.
Step 2: Folding the Paper
Okay, now let's start the process...
After getting your suitable paper, create a small fold at the bottom, and continue folding up, until you have a open space at the top...
Step 3: After Folding the Paper Up...
After you have finished folding the paper almost up to the top of the paper, fold it in half, so that the fold is sticking out on the outside, like so:
Step 4: Folding the Paper Again
After it is folded in half, grab the tip (shown in the image below) at the top of the paper, and pull it down below the folded part, as once again, is in the image below:
Step 5: Firing It Off!
After the tip is folded down, grab the end of the paper cracker, and whip it down really hard *BANG*! The result does vary, but if done correctly, it should always make a loud bang after the first try. But be warned, these things do rip after a while, and their sound diminishes.
After the paper cracker has been "fired off", you should notice that part of it has unfolded down. Refold it up, and repeat step 4. That's how you "reload" it.
Yours not working? I can probably tell you what's wrong. Leave a comment if you're having trouble...