You use the San Fran Rule to avoid lengthy indecisive discussions about what restaurant to eat at or what to do next weekend. The first person will tell the other(s) to give 3 choices and the first person MUST pick from 1 of the 3 choices. If more than 3 choices are given, only the first 3 mentioned will be considered. This can be applied to almost anything: what workouts to do with your workout buddy, what club to go to next weekend, etc.
Origins: Circa 2001. You can easily spend 45 minutes driving around San Francisco (or any large city) for both a restaurant and parking because nobody can make up there mind because of all the choices. This has been tested and in use for almost 20 years, and 3 is the perfect number, no more no less.

A term used to reference cannabis/marijuana/weed.