A a term used to describe that is gay but is generally used/accepted by straight people. The gayness can stem from a design in a product, a feature in a thing or an aspect of the thing. When a straight person interacts with this thing it arouses a minor suspicion that they might be gay.
The product may not however involve anything to do with gay sex or other things that are blatantly gay.
Things that are San Francisco gay:
Apple Products, Organic Foods, Expensive Designer Clothes
Things that are NOT San Francisco gay:
Kissing Dudes, Will and Grace, Prius's