It's Always Sunny in Philadelphia Season 6 Episode 10
Charlie Kelly: King of the Rats
When the gang thinks it's Charlie's birthday, they try to throw a surprise party for the unappreciated guy. Dee is sent to distract Charlie with a spaghetti (spa) day at the movie theater, while Frank tries to organize the party. Charlie gets confused during the 3-D movie and attempts to leave so Frank ambushes him and takes him to real spa day. When they return, Frank reveals it's actually his birthday and the guys feel tricked and no longer care. At least he has his bridge friends.