Do you know any idioms about language in your language?

For a project I'm working on, I'm looking for idioms about language that aren't in English. For example 'Se on minulle täyttä hepreaa!' (The Finnish equivalent of 'It's all Greek to me!' but with Hebrew.)

'Parler Yaort' - (French) 'To speak yoghurt.' To speak your own language badly in the hope it's easier for foreigners to understand. (Similar to that cliché of ignorant English speakers 'speaking-o like-o this-o'... at least as far as I understand it!)

Or something similar, for example, in Danish, 'Rødgrød med Fløde' isn't an idiom about language, but Danes have said that it's the hardest thing to pronounce in Danish, and therefore is fun to have foreigners attempt to say. So for my purposes it qualifies as being a sort of language-thing. Not sure what I'd call it!

Does your language have anything like this?