Last night, comedian Jimmy Fallon took over iconic late night show The Tonight Show (previously hosted by Jay Leno for over 20 years). Guests included Kim Kardashian, Lindsay Lohan, Mariah Carey and Lady Gaga, no less. Now, you've probably been laughing to some of Jimmy's jokes for years now (he is still one of our favorite ever SNL stars), but here are five videos that prove why he's the boss of LOL o'clock.