You don’t have to give yourself such airs.
WTF does this even mean in English “You don’t have to give yourself such airs.” what does this mean??? its not even slightly close to the translation either. maybe 2 words are shared?!.. No one learning this would ever be able to get this, nor would any German… hell, no Englishspeaker would be able to even get the English translation by itself!
I haven’t heard this prase before either, but wiktionary does have an entry for “airs”: airs - Wiktionary, the free dictionary
- Affected manners intended to impress others
I would consider “put on airs” to be a reasonably common expression, with “give oneself airs” being an alternative. Here are the Wiktionary entries -
put on airs - Wiktionary, the free dictionary
give oneself airs - Wiktionary, the free dictionary
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Look, someone even made a Wikipedia article for “put on airs” 
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Put on airs - Wikipedia
“A reasonable common expression” where are you from? I don’t care that you can find a use case for its potential use on Wiktionary.
As a native English speaker, this expression has never been uttered by anyone, even in passing, shows, media, games, school, in my entire life. If it something that a native speaker would not be able to get without looking it up, it does not deserve to be on an app that is teaching people a language.
I can find slang on Urban dictionary too, that doesn’t mean anything that 1 and 1/2 people used the phrase once