The idea behind viral marketing is simple: Create something that delights people enough that they feel compelled to share it with friends and family. The execution, however, is the hard part. But KFC and Burger King are recent examples of viral marketing gone right. On Oct. 19, 2017, a user noticed that KFC's official Twitter account follows only six men named Herb and all five Spice Girls. In other words, 11 herbs and spices – the ingredients used in KFC's secret recipe.