An amusing German expression for saying: to do something without much effort, effortless or I could do it on my head = I kann das im Schlaf. Literal meaning: I can do that asleep.
When you get involved in a fight or disagreement with someone, or to quarrel with someone, a hilarious German expression is made use of: Sich mit jemandem in die Wolle kriegen or mit jdm. in die Wolle geraten. Essentially: to obtain into the woollen with somebody
The English expression: to show someone up, to tell somebody off = Means in German: Jemandem aufs Dach steigen. Essentially: to climb on someone's roof