...they were returning to San Diego from an "airshow" at Mather AFB (Sacramento, California)-- apparently still in the airshow frame of mind & attitude.
Lake Tahoe is a popular resort area, with lots of people around.
Can probably chalk this one up as still another airshow-related mishap.
The stunts that military pilots pull (both successfully & unsuccessfully) while away from home-base supervision... would fill this forum without end. Been going on for nearly a century around the world.