Once, a German waiter couldn’t understand me and even corrected my accent when I ordered ‘pommes’ in the French way (I mean, as I learned it: [pɔm fʀit]).

Me: I would like pomm frit, please.
German waiter: Excuse me?
Me: Pomm frit.
German waiter: You mean, pommeS friteS?
Me: Excuse me?

If you are German, and pronounce it in the German way, so, please, gimme two peanuts.

TO HAVE A PIG

If you won the lottery, or you’ve scraped through an exam to which you haven’t studied, or you even don’t need to do something that you didn’t want to, so you had a stroke of luck! In German, it is said that you had a pig, or ‘Schwein gehabt!’. Pigs, indeed, are used frequently in everyday language. There’s no one around? ‘Kein Schwein [niemand]' (no pig/no one) has been here. Felt sorry for someone? S/he's a 'armes Schwein' (poor devil).

ALL CUPS IN THE CUPBOARD

If someone doesn’t have ‘alle Tassen im Schrank’, then that person is kinda mad. An English equivalent would be ‘not have all one’s marbles.’

I ONLY UNDERSTAND TRAIN STATION

The German phrase ‘Ich verstehe nur Bahnhof’ doesn’t mean that one who says it understands the language of the train stations. The term is similar to ‘It’s as clear as mud,’ or ‘It’s all Greek to me,’ or ‘It’s all double Dutch to me’ in English.

LIFE IS NOT A PONEY FARM

When things get tough, a German can tell you that ‘das Leben ist kein Ponyhof.’ In other words, life ain’t easy.

MY NOSE IS FULL

'Ich habe die Nase voll' can be interpreted as someone in need of a tissue. In German, however, it means that the person is sick and tired of something.

HOPS AND MALT HAVE BEEN WASTED

A list of expressions in German cannot leave a reference to beer out, can it? If a situation ‘Hopfen und Malz ist verloren”, then you better give up because it’s a hopeless cause. The expression, of course, has its origin in beer production: if something goes wrong during the process, then the malt and hops have been wasted and it’s no longer possible to produce a good beer. The expression can also be used to refer to someone: ‘An ihm ist Hopfen und Malz verloren’, i.e. ‘he’s a dead loss,’ or ‘he’s hopeless.’

HAVE A GOOD NIGHT PARTYING

This one was really interesting to me, because in the beginning I thought that people were really wishing me a good night partying out. But, I wasn’t fu**** going out, so what the f****? Now I know that for the same reason why when Australians say ‘beer o’clock’ it doesn’t (always) mean they’re going for a beer, if your coworkers tell you ‘schönen Feierabend’ after a working day, they’re simply telling you that it’s home time.
And it wasn’t enough to find this meaning out, but also that the expression can be used at any time of the day. For example, once I listened to another cowork saying ’schönen Feierabend’ to one who was leaving around midday just because the rest of the day is worth as ‘night of celebration.’

THAT’S SAUSAGE TO ME

Now that you’ve left work, you may be open to suggestions on how to spend the rest of the day. If it doesn’t matter what you’d like to do, just tell your friends ‘es ist mir Wurst,’ and they will know you’re not talking about sausages, but that it’s all the same to you.

PRESSING MY THUMBS

When your friends wish you good luck, they’ll say ‘ich drücke dir die Daumen.’ And they may even raise their hands to make the gesture. They mean that they keep their fingers crossed for you.

LIES HAVE SHORT LEGS

This one is self-evident. As in English, ‘Lügen haben kurze Beine’ means that a lie never lives to be old.

Text translated (with adaptations) from the Deutsche Welle article.