If you fold the twenty dollar bill correctly you can spell the name OSAMA. Osama Bin Laden is the mastermind behind the whole 9-11 attacks.
Also, you can fold the twenty dollar bill to spell ARAFAT (reading it from
right to left which is the correct way in Arabic). Yasser Arafat was once a
famous Middle Eastern terrorist, although he now supports peace instead.
Another intersting fact: 9+11=20 and this is all on the 20 dollar bill.