How do you respond when people judge your SW degree/career choice?

I'm starting an MSW in the fall and something I've run into quite a bit are people who 1) don't understand what social work is 2) think I'll spend the rest of my life taking custody away from awful families or 3) gawk at the fact that I'm taking out some student loans to cover the education. Granted, I'm a first generation college student so part of it is just lack of familiarity with graduate programs...at least with family members. I'm guessing I'm not the first to hear this sort of talk. How do you reply?