When people come to visit you in SF (which they always do, because: SF), you inevitably end up dropping knowledge bombs left and right. "Did you know the fortune cookie was invented in San Francisco? By a Japanese guy?", or, "the Golden Gate Bridge was originally supposed to be painted black with yellow stripes". What about the fact that "the city's cable cars are the only National Historic Landmark that move"?
And while it's awesome that you love to share how smart you are, did you also know that when you said THESE 11 things to your tourist friends, you were actually telling them huge, fat lies?