What does 'junk' mean

Major bond rating services now all agree that Greek government issued bonds are 'junk'.

Bonds are rated from AAA to AA, down to Ba to Bb.  That describes the probability of the bonds reaching maturity, paying dividends the entire time and being worth 100% when it is time to redeem them. AAA means 100% probability and the current Greek rating of Ba means less than 50% probability of getting your expected money back.

I've bet on Ba bonds in the past and made a lot of money when they paid off.  Michael Milken was the genius who created a vast market for low rated bonds that had a greater likelihood of paying-off than the bond rating houses estimated.

But Greece is a socialist mess.  The 'junk' rating is accurate. (The final blow to the straw house of the Lefty ideology; socialism doesn't work.)

No one I know believes the Greek government can work themselves out of the excessive government controls and subsidies of everything and the rampant employment of friends and family ('corruption') to do nothing. 

Most people I know think Greece and a few other socialist countries will have to leave the EU on their own accord so they can slap their citizens with a wild inflation. Greeks will apparently prefer the hidden punishment of inflation to openly visible increases in taxes and decreases in income.

***PS Take a look at Alex's comment below.  China is buying Greece.  There may be another way commerce will solve this problem.