Let me preface this by saying that I have a whole range of "proper" glassware and I would not normally drink out of a styrofoam cup. However, necessity requires that I drink covertly (my son is in the hospital, and I'd rather not advertise that I'm enjoying a homebrew in his room after a long day talking to doctors).
What is happening when I pour an otherwise well-carbonated homebrew into a styrofoam cup? It's near impossible for me to do without an enormous head, and the beer tastes flat in the cup. My theory is that the bumps create tons of nucleation points that make the beer foamy and flat. Admittedly, this is a half-baked theory, with nothing to back it up.
So what's going on here? Just curious, really.