I've been to the Folsom Street Fair 5 out of the past 6 years. I love this event. I find it to be (for the most part) a place of acceptance where individuals of differing sexual persuasions and fetishes are appreciated and celebrated. Folsom is also does a magnificent job of matching BD/SM with raising money for good causes, such as paying to get spanked for AIDS and breast cancer research.
Another part of Folsom Street Fair that I particularly love is the game of dress-up that I get to do before going. I've worn all kinds of outfits - only underwear once, a corset twice, liquid latex another year and most recently electrical tape. I love how the crowds of eager photographers swarm around interesting outfits (mine frequently being one of them) and take photographs as if they are the paparazzi and the costumed people are celebrities. I, being vain and extroverted, find this situation highly enjoyable.
I think I'll make a top 10 list of unusual and wild things I've seen at Folsom over the years:
1) A booth that was advertised as "The Human Urinal" with eager pee drinkers and bathers.
2) A man holding a platform up with a chain connected to his balls. People were encouraged to place items on the platform.
3) A gay porn actor, standing on the counter of his porn-house's booth, masturbating to ejaculation on a jubilant crowd.
4) This guy with the cow tongue over his penis.
5) A gay porn actor sucking his own penis.
6) A person being pulled in a carriage by another person dressed as a horse.
7) People with bells sewn into their skin performing a group dance.
8) A man with "HIV+" tattooed on his penis.
9) A woman walking around the fair with a doll to her breast, as if she was breast-feeding it.
10) A handcuffed, gagged, and leashed woman with an electric, remote controlled buttplug. Her mistress was letting participants in the crowd take turns toying with the remote controller.