What do we mean when we say it today?
We've changed the phrase again today, although ever slightly. Usually, people say, "It's all Greek to me" just to emphasize that everything was unintelligible. And it's not just with foreign languages that this phrase is used. We use this today to mean anything that doesn't make sense—from advanced calculus to Lady Gaga's latest hairdo.
We hear this all the time. It's really just a fun way of saying you don't understand what someone is saying. It sure is more polite and funny than just saying "huh?!" all the time, or walking around with a perplexed look on your face. So give it a try. We bet you won't feel as bad asking people to repeat themselves or explain what they meant when using this little catchy phrase.