It is time to start printing the New Drachma - FAST
There was a time when Greece thought it would be a good idea to join Euro zone. This gave the Greeks a strong currency with which it could borrow much too much money.
So they borrowed too much money. But at a certain point they realized they could not pay it all back.
The Greek government asked more and more money to pay the interest on the money they already borrowed. Somewhere along the line they forgot how to do arithmetic.