" Swarley " is the of How I Met Your Mother , originally aired on November 6, 2006 . It is widely considered one of the series' most iconic episodes due to its titular running gag and the introduction of the "Crazy Eyes" theory. ☕ The "Swarley" Nickname
: The episode ends with Barney walking into MacLaren's Pub to the Cheers theme song, with the entire bar shouting "Swarley!". 👁️ The "Crazy Eyes" Theory
: According to Barney, crazy eyes are a warning sign of an unstable personality.