Could you help me with this German sentence?
I've just started studying German and I watch movies with German subtitles. I came upon this sentence, I know it is a bit vulgar one but I have to ask this.
One of the characters said this to another : You are an ass. And it was translated to Du bist ein Arsch. I have looked it up on Google and it has ein everywhere before Arsch.
But why? Arsch is Der Arsch and not Das Arsch, so should not it be Du bist einen Arsch?
Thank you for the answer in advance! :D