Clad in a chef’s hat, Curtis Kimball ladled pancake batter onto an electric griddle as hundreds of hungry neighbors lined up for one of his fluffy flapjacks. It was a pancake party, and Kimball, 43, hosted it on the front driveway of his home in San Francisco on Feb. 12. This was the second such event; the first he kicked off in late January with a few funny fliers. “My wife says I’m getting weird,” Kimball typed on sheets of paper, which he then taped to telephone poles around the Bernal Heights neighborhood. “She says I need to make friends....