It’s Always Sunny in Philadelphia Season 6 Episode 4 (It’s Always Sunny in Philadelphia s06e04) with title “Mac’s Big Break” aired on Thursday, October 7th 2010 at 10:00 pm via FX Network.
Here is summary for :

Mac finally gets his big break after correctly answering a radio station’s trivia question. Meanwhile, Frank, Dennis and Dee start their own bar-banter podcast.