Jimmy Fallon, host of NBC's The Tonight Show, and one of the most popular entertainers in the world, is also a father. His children's book is funny and warm and adorable—just like he is. Your baby's first word will be . . . "Dada!" Right? Everyone knows that fathers wage a secret campaign to ensure that their babies' first word is "Dada!" But how does it work? One of the most popular entertainers in the world and NBC's The Tonight Show host, Jimmy Fallon, shows you how.