How Rude

Yesterday while eating my lunch, a co-worker came into the office and made a comment: "Salad? Are you on a diet? Ugh! Rabbit-food!". I mostly rolled my eyes and ignored them, but mentally I thought "I happen to LIKE salads, yes I am on a health diet, and it is none of your bee's wax.". Because I actually like this co-worker, I refrained from saying what was on my mind, however, I have had people I barely know make comments to me about my eating habits before. Most of the time, unless I am friends with said person, it is rude. So OF COURSE this made me think of a small list of other comments/questions that are rude to ask people (in my own opinion, and again, unless...