Shorting the US Dollar
Probably the most common (and liquid) way to short the US Dollar on the ForEx, or foreign exchange for currency trading, is to buy the EUR/USD currency pair. In essence, you are buying Euros with US Dollars.
If you believe, like I do, that the economy is going to be in the tank for along time as Washington politicians spend and print money like drunken sailors and devalue the currency, then there is only one direction the USD will go in the medium to long term: Down.