One of my recent concerns was that hyper-inflation will hit and that our currency will become funny money... The idea of using a wooden bill was first done by the German's whose currency was devastated after WW I. They knew the bills would quickly become collector's items, hence helping to stabilize the temporary wooden bills!
But this is no laughing matter... nothing involving currency ever is - especially counterfeit money. The US had such a problem with this that all 13 colonies publicized that if you conterfeited the money, you sould be killed. We've always been a county in favor of the death penalty (and this is before Texas was part of the US).