The term "Happy Hour" is often ascribed to the time on board Navy ships that sailors were allowed to box or wrestle to relieve stress. Since San Francisco has a long and storied Naval history, it's no wonder that the city boasts one of the most impressive selections of Happy Hours of any U.S. City.
None of the establishments encourage boxing, but all definitely work hard to relieve stress. If you feel like a gritty dive bar, Dave's downtown is a San Francisco institution. If you want your dive with a slice of free pizza, try Sutter Station on a Friday night. If you need something fancier and want to get swept up in the craft cocktail movement, try Agave or Alembic Bar.
Happy Hours encourage everyone to let their guard down, so it's a perfect time for locals and tourists to mix. If you're a real planner, choose a happy hour by the neighborhood you're most interested in exploring.
For example, if you want to know about the Mission District, which is at the center of all the social and technological upheaval going on in San Francisco, belly up to the bar at Blondie's. If the guy next to you won't talk, there's nothing like getting the real lowdown about a city from a bartender. Remember: bartenders see everything.