Ok I just had to post this right now. This video shows a flash mob in Seattle dancing to Glee songs. I've always underestimated flash mobs. Like, I always assume that it's going to be a small group but a wide angle shot of the crowd showed almost everyone dancing. It's amazing that in the beginning, you never know who's part of it, then you'd be surprised at the "randomness" of people who don't look like dancers join in, and the whole thing erupts into one amazingly choreographed number.