Why Because

16-yr-old girl, who last week dealt with C# major and its key signature of all sharps. 

Me: Why does C# major have all sharps?
Girl: Because it's C# major.
Me: But why?
Girl: Because it has all sharps.
Me: You've just told me that C# major has all sharps because it's C# major. 
Girl [slightly apologetically]: I know...  That's what I usually do in exams if I don't know the answer, I just rewrite the question in a slightly different way so it sounds like I know what I'm talking about.

Honest.  She then tried to tell me this is the scale you learn first on violin, even though last week she was scared just looking at the key signature.