How I Met Your Mother ran for nine seasons and is packed with fun trivia—Barney’s legendary “Playbook” was even published as a real book, and the blue French horn quickly became one of the show’s most iconic symbols. Guest stars like Britney Spears and Katy Perry made memorable appearances, while Alyson Hannigan and Jason Segel, who played Lily and Marshall, famously pretended to eat during their food scenes instead of actually eating.

