After Greece joined the EU, the country went on a spending spree financed by cheap debt, which now has come back to haunt it. S&P recently downgraded Greece's credit rating all the way to "CCC", the lowest for any country in the world. To pay down the debt, Greece has been selling prime assets such as telecoms, banks, ports and even part of Mykonos. Still, Greece will likely need another bailout from the European Central Bank. If Greece goes down, financial contagion could spread throughout the EU. America's debt is rated AAA for now. But with the US' massive debt load, how much longer can this go on?