“Das ist der Hammer!” is a German expression and means literally “this is the hammer”. It sounds very weird when translated and you realise how stupid some expressions are in your mother tongue. I tried to find the origin of this expression, unfortunately I wasn’t successful in my search.
Now you are wondering when, we silly Germans are using this expression. Das ist der Hammer is a colloquial expression. It can be used to express both positive and negative surprise, disbelief or the sense that something is brilliant or wicked.
For example, when seeing an amazing sunset you could say “Das ist der Hammer!”, but also in incredibly disappointing situation such as somebody ripping you off. You could probably translate it with “Damn it”!
So next time you are amazed in a situation, think of your tool box!