There's a mistaken belief in today's working world that leaders need to be serious all the time to be taken seriously. The research tells a different story. Based on the course they teach at Stanford's Graduate School of Business, behavioral scientist Jennifer Aaker and corporate strategist Naomi Bagdonas delve into the surprising power of humor: why it's a secret weapon to build bonds, power, creativity and resilience -- and how we can all have more of it.