I want people to think?

I work in a diner full time: I'm saving for school. Basically everyone at the diner thinks I'm ditzy because my dad says things like, "She's actually a natural blonde" to the people there. I finished my first year of pre-med school (just a little college program, but I still got a 98%). When I tell people this, they don't believe me, and it's hurtful. I want a career that people can tell I'm intelligent and will give me credit for my knowledge. Any suggestions?