For some years, since I first read Wittgenstein as a 15 years old, I have been slightly annoyed by his use of N.N. as a place holder for a name. That’s because I have been ignorant of what it stands for. But then again I have not been bothered enough to go and check.
N.N. turned out to be an abbreviation of Latin phrase “nomen nescio”. Now, enlighted by wikipedia, of course, when N.N. is used, I do know that I do not know the name of the person referred to. And I am bothered no more?