The prank was pulled not by her family, but by a museum. Believing that a 'shark tank' exhibit was real, the woman puts her hand on the tank glass, only to be shocked when the a great white charges full speed at the window. She falls over backwards, but is able to laugh at herself as she gets up. What a good sport.
Lesson learned: When you're in an exhibit called "Exquisitely Evil: 50 Years of Bond Villains," in the International Spy Museum, it's probably best to expect the unexpected.