aka showing your open palms to someone
Talk to the hand
About two weeks before we left for Porto Rafti, I decided to look up all the faux pas Americans make while in Greece so I wouldn't look like a complete tourist while over here. One of the mistakes that supprised me was waving to people you see in public. Why would something that is considered inviting back home be seen as an insult here?
The moutza, or showing the palm of your hand while spreading your fingers apart, dates back to the Byzantine empire (330-1453 A.D.) when the officials of a city would parade a criminal or prisoner around the city to humiliate them. They would make them put cinder (Greek moutzoura) on their hands and cover their faces with it to add to the victim's shame. Soon it became an insult just to show your palms to another and it has stayed this way for hundreds of years.
I must admit, the other day when we were in Athens I forgot that I was in fact not in the US and I openly waved to a group of friends I saw passing by. However, I don't think any of the natives thought I was being disrespectful to them. From what I've gathered, the people here understand that a lot of the world views a hand wave differently than they do and will sometimes even wave to their friends. But if they were to use the moutza, their intent would be obvious.