A very serious sociological topic. The use of "phony" as a pejorative term works because people in our society are expected to have an authentic, unique essence "beneath" their social roles ("the real me"). Ironically, the whole concept of the unique, independent self is a product of social interactions, so when people opens up and share something about who they really are, they're playing out a social role, just like a student in a classroom, a worker in a cubicle, or Lady Gaga at the music awards. Irving Goffman is notorious in sociology for arguing that people are like onions; if you peel away all the layers of social roles to get to the essence of a person, there's nothing left.
So--in this sociological sense, we're all phonies!
Miles