When we  speak our native language, we don't realise how we pick up more than just words alone.  There are many different phrases and sayings that would not translate well into a foreign language.  Look at this conversation by an Englishman, and how it would need to translate for a German in order for him to understand it:

"He can't make head nor tail of it.  He's not as thick as two short planks, but he did cut off his nose to spite his face.  He really is burning the candle at both ends but now once bitten, twice shy. He does fly off the handle, but then, it's merely a storm in a teacup.  Mind you, it's all just Greek to me."

He won't get clever from that.  He's not as dumm as bean straw, but he did cut into his own flesh. He really is putting his health on the line, but then, a burnt child avoids fire. He does get out of his own skin, but then, it's merely a storm in a water glass.  Mind you, I only understand train station."  ......beware the literal translation!