In Greece they don't drink a lot of cow's milk, so if you ask for a glass of milk when someone offers you a drink, you might get condensed milk mixed with water.
The first time I went to Greece when I was 12, this happened at my cousin's house. I thought it was the nastiest thing ever, but 5 years later, after having gone every summer, I really developed a taste for it! Can't say I've drank it since, but I still remember the flavor. Definitely not like milk, so if that's what you're expecting, it's not going to work out for you. Kind of like soymilk.