When during a very serious conversation you start quoting words of wisdom from Yoda. And you know your talking to another SW fan when they start to reconsider what they were thinking based on that wisdom.
When you can tell how far into the movie its at, whats about to happen, and what the characters are about to say just by overhearing any 2 second sound effect or piece of music while not even being in the same room that the movie is playing in. Your a true fan if you enjoy impressing the hell out of people by doing this. I know I do. 😮💨