Last night saw comedian Jimmy Fallon take over America's iconic chat show The Tonight Show (previously hosted by Jay Leno for over 20 years) and everyone is talking about it. Guests included Kim Kardashian, Lindsay Lohan, Mariah Carey and Lady Gaga. Casual. Now, you've probably seen a few of his sketches on YouTube before (he was a former SNL-er, after all) but take a couple of minutes to watch these five videos that prove why he's the new king of late night.