Charlie day of "It's Always Sunny In Philadelphia" fame appeard on "Conan" Monday night and gave an entertaining interview with a lot of funny, behind-the-scenes details on the show.

For example, Day said that when the show started the gang didn't realize the studio would pay for offices and lunches, so they had to keep coming up with their own solutions. This just confirms our suspicions that the actors on "It's Always Sunny" are just as funny as their characters.

Conan's audience got some inside info on Day's character Charlie, including his product Kitten Mittens and his notorious alter-ego "Green Man." After seeing an audience member already wearing the green suit, Day and Conan discussed whether or not you should be naked underneath and if you can drink alcohol through it or not.

All of Day's interview was solid, but the best part comes at about 5:00 in, when he talks about the April Fool's Day prank he and the gang pulled on Danny DeVito. Let's just say it involves DeVito's character, prison rape, and ends with a call to his lawyer.

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