Greeks use Chinese as the canonical example of an incomprehensible language.
What's interesting is that although the "It's Greek to me" colloquialism mostly refers to the fact that the Greek alphabet seems incomprehensible to the (non-classical-humanities-educated) reader, Greek has actually a very complex grammar: Everything is conjugated, everything has genders, and you have to remember the correct form of every noun, preposition, article, pronoun, etc. In comparison, Chinese grammars are amazingly simple.
Most Greeks don't take notice of this fact until they see somebody struggling to learn Greek as a foreign language.