Justin Timberlake [1] and Jimmy Fallon [2] opened Saturday Night Live [3]'s 40th anniversary special with a rousing rap, highlighting the show's many iconic characters. Think "Dick in a Box," more cowbell, and "The Ambiguously Gay Duo." They even had some guests: Rachel Dratch showed up as Debbie Downer and Molly Shannon as Mary Katherine Gallagher — smelly armpits and all. It was a pretty spectacular way to start the show, given that Fallon and Timberlake have been at the center of so many recognizable moments. Take a look!