Euro Notes: MM, the Undergrad, and The Greek Debt Bomb

A confused undergrad recently asked me what was going on with Greece's astronomical debt and bankruptcy issues (along with the political fallout).

I said, "The problem is that it's about to destroy the eurozone."

Am I oversimplifying? What's an "easy" way to explain the mess? Help me out here, people.

(Interestingly, this was in a class that had nothing to do with modern Europe. But it was definitely a teachable moment. Besides, the kid asked me first, so I felt perfectly OK to tell the whole class about how DEBT IS BAD and how UNRESTRAINED NATIONAL DEBT WILL TURN AROUND AND BITE YOU-- while hoping that the bright ones would understand I meant all debt, not just Greece's.)

Meanwhile, Euroskeptic Brits are feeling, understandably, rather justified in their doubts about joining the euro currency.