I try not to, but I'm sure we all do at some point. The only time I recognize I'm consciously doing it is when the person pushes their stereotype on me. If somebody walks in wearing the whole gangsta get-up full with bandana and yo yo yo's, or some guy wearing make-up and going "Betch, please," then I assume they want me to think of them as a tough gangster or a nelly retard, and then all those accompanying attributes.