Ways to say you don’t understand

Formal short phrases you can use: Pardon? Sorry? Excuse me? I beg your pardon?

Informal short phrases you can use: What did you say? Huh? ‘Scuse me? What was that? Hmm?

Now, let’s see some slang phrases: Come again? Pass that by me again? I don’t get it

And some idioms: ((Idioms aren’t translated literally)) This is all Greek to me I think our wires are crossed That was as clear as mud Everything you said is just a word salad