As with most things Greek, Apokries dates back to Ancient Greece, thought to be celebrated as a worship to Dionysis, the God of Wine & Feast.
In Greek Orthodox religion, Apokries is the period of time before Lent. The word literally means "Goodbye to Meat," Apoxh-apo-kreas. Interestingly in the Latin language, Carnival also has the same translation: "Carne" = meat "Vale" = goodbye.
Apokries runs for three weeks before Lent: in 2013 the dates are Sunday 24th February to Sunday 17th March. In this time, many fancy dresses can be bought and street celebrations occur. A majority of the street parades occur on the last Sunday (2013: 17th March), but today I attended one in the Metaxourgeio/Gazi district of Athens.
See this video by Athens Living as testament to the fun and frolics had by all (no translation of the song by women dressed as traditional village Greeks, wielding cucumbers needed I think).
Yes, Greece may be going through a crisis, but people still know how to have fun: young and old, male/female - all contributed to the fun and joyful atmosphere.
To round of the carnival time of year - the largest carnival event in Greece, and one of the biggest in Europe, takes place in the Greek city of Patras. They also celebrate throughout the carnival period, but their piece de resistance comes on the last weekend of the carnival.
Saturday has the " Nihterini Podarati," Night Parade on foot and Sunday is the closing ceremony: burning of the float of the carnival king, countless parades, fireworks dances & concerts. It takes place at the port and is broadcast on television.
So come to Greece to celebrate carnival. You'll be welcomed with open arms. Opa!