This is pretty neat. I will show you how to make a 20 dollar bill turn into the twin towers falling.
Step 1: First Fold
First you need to make well this is what I call it a hot dog fold.
Step 2: The Next Fold
Next you need to make the fold that I did in this picture.
Step 3: Your Now Allmost Done
Now you just need to make the same fold that I did in the last picture only you need to make the fold on the left side instead of on the right side.