Vienna has over a million inhabitants plus tourists. I guess, that i only know at max 0.2% of its population by name. When i moved here from a small town, where everyone knew everyone, i guessed, that it would be quite unlikely to meet someone i know accidently at a neutral place and that i could travel around in the city easy without being recognized.
But i regulary bump into someone on the subway, which is most of the time a pleasant surprise to me. Yesterday it was my former flatmate Raed, which i had lost contact several years ago.
So if you see me somewhere in the city nose-picking or doing other silly things, just say hello to surprise me :-).