Das gab mir einen Fall der Nerven
Indeed, I would not understand this, either.
I think the reason is not so much that German native speakers do not extrapolate or assume language to be rigid in general, but that elements of this particular phrase are close to other expressions than the intended ones, thereby leading to confusion.
Let's look at what I mean one by one:
ein Fall
This word has multiple very different meanings in German, in particular:
- a case, similar like in English, talking about an occurrence of something, e.g. medical or criminological
- a drop, the action of falling
ein Fall der/des ...
When I read "Fall" coupled with an (inflected) definite article like this, I kind of assume the less abstract, second meaning to be the intended one. "Ein Fall der ..." - ok, something has fallen down.
Curiously, had you translated a bit more word-by-word, you would have arrived at "ein Fall von", which might have rendered the phrase slightly more comprehensible in German. "Ein Fall von ..." is commonly used in German to refer to the concept "a case of ...".
gab mir einen Fall
This is confusing because in German, "jemandem einen Fall von ... geben" sounds like "assigning" the case to someone. This might be a case of a certain medical condition assigned to a given doctor, or a criminal case assigned to a commissioner, but the target of "geben" is the one handling it, not the victim.
Typical verbs to express what happens to the affected person with respect to the "case of something" would be rather "werden" (because the person is or becomes the case), "haben", or "erleiden".
ein Fall der/von Nerven
Lastly, it is not quite clear what "Nerven" is meant to express here. As the full expression is not a set one with a fixed meaning, we can only go by the word "Nerven", and that is used in multiple meanings again:
- It can mean something like what you wanted to express, that someone is really unsure/nervous about something - the words "schwache Nerven" and "Nervenbündel" point into that direction, or, as suggested by Henning in his comment, "jemandem flattern die Nerven" or "mit jemandem gehen die Nerven durch". IMHO, while well established and comprehensible, these latter two expressions are almost a bit "colourful" and maybe not in everyone's active vocabulary.
- It can also mean that someone is annoyed by something, as in "something gets on someone's nerves" - "etwas geht jemandem auf die Nerven", for which there is also a single verb: "etwas nervt jemanden". These expressions are extremely common.
- At the same time, it can also mean quite the contrary, that someone is especially bold or brazen. To my knowledge, this is expressed with a singular in English, like in "someone has the nerve to do ...", but in German, it's the plural in this case, as well, typically in the exclamation "Der/Die hat [vielleicht] Nerven!"
Outside of the last phrase, it should be noted that "Nerven" is pretty much neutral. "Nerven" simply are a part of the body, which is neither good nor bad. Therefore, "ein Fall von Nerven" doesn't quite work, either, because you expect something "problematic" or at least "noteworthy" when there is a "case of something". "Ein Fall von schwachen Nerven" would be clear, but "ein Fall von Nerven" sounds just incomplete.
In all, encountering a phrase for the first time is, in general, okay and the meaning can often be deduced from the individual parts in German. But in this particular case, most of the individual parts can have mulitple meanings, sometimes even contrary ones. Thus, it is quite hard to find out what it is supposed to mean.
