As a rule of thumb, I don't bring up being a Ph.D. student with people outside of my department unless they ask me about it first, e.g., "what do you do for a living?" and then I tell them; the idea being that if you're modist about it and realize that it's just a job like any other, then there's no implication of "I'm better than you because I'm more educated." For me, this boils down to the same situation as back in high school where people try make you feel bad for taking difficult classes. People are always going to get on your case for stuff like that. As long as both of you are contributing to society, there's no reason for one to be demeaning to the other because of their education, but that's life.