Mein Deutsch ist kaputt
Is it correct to say "Mein Deutsch ist kaputt" to say that "My German is Broken"?
No, it's good for a laugh though. ;-)
So your suggestion might even trigger more help than a proper sentence.
Mein Deutsch ist (leider/ sehr/ noch) schlecht. Or.
Mein Deutsch ist noch nicht so gut. Does inject a bit of an optimistic spin.
As already said it is usually only for things, but you can say:
Ich bin kaputt.
which can mean: I am not functioning well. (eg after a long night and drinks... and comparing yourself to a broken machine) or you are really feeling a burn out.
Technically, you can say "Mein Deutsch ist kaputt." It is something I used to say, although I agree that context is absolutely necessary to convey what it means.
For a time after I returned from an extensive visit to London, I would accidentally get stuck in an English sentence structure. Naturally, the German language did not comply. In those instances, I did say "Mein Deutsch ist kaputt / im Eimer." ("My German is broken / in the bucket/bin.")
When I got stuck and had to do the sentence over, people would laugh as they understood "Mein Deutsch ist kaputt" as a joke. Other times, I would add the explanation so people could understand what I meant with it.
On its own, it's confusing and doesn't really tell people anything. But with context, I don't see a problem with "Mein Deutsch ist kaputt." It's grammatically sound and not a sentence outside the realm of possibility.
Thank you for the input, guntunge!
First things first: "kaputt" literally translates to "broken". With the meaning of "my German ain't so great" in mind, of course "kaputt" cannot be used. "Gebrochenes Deutsch" is accurate. No doubt and no argument.
As to "out of order", it literally translates to "außer Betrieb". A machine can be "außer Betrieb" and it can also be "kaputt". "Außer Betrieb" can translate to "broken" as well, that is true. (I would say, at this point, that there are many ways to skin a cat, but mine is watching me type.)
Example: "Mein Auto ist außer Betrieb" is a bit weird. "Mein Auto ist kaputt" is common. (mein Auto = my car)
Example: "Der Drucker ist außer Betrieb" is valid. As is "Der Drucker ist kaputt." (der Drucker = the printer)
I'm a native German speaker, not English, so I cannot speak with authority on what is "out of order" and what would be weird to be called such. It's mostly true in German, but you can get creative.
For a mean example: "Dein Hirn ist jawohl außer Betrieb!" -- "Your brain must be out of order!"