I took a long time to finish my Ph.D. I won't rehearse the litany of excuses reasons here, but suffice it to say that I endured the 'how's your thesis?' question for far too long. After that it was 'when are you going to finish your thesis?', and finally it was 'are you actually doing a Ph.D at all?'. It wasn't just my supervisors either: friends, family, passers-by.
I regret not buying a t-shirt I saw in Cambridge, which read 'DO NOT ASK ME ABOUT MY THESIS'. Here's PHDComics' explanation of the social minefield of postgraduate research: