The sixth season of It's Always Sunny in Philadelphia, premiered on FX on September 16, 2010. The season contains 14 episodes and concluded airing on December 9, 2010 with the hour-long Christmas special. An additional episode called "The Gang Gets Successful" was produced for this season, but was not aired, despite scenes from the episode being included in promotional material for season 6. It was later re-edited with new scenes to create the Season 7 episode "How Mac Got Fat".
Mac defends traditional marriage, while the rest of the gang reaps the rewards of wedded bliss.
Marital bliss turns into business, as the gang experiences the emotional and economic hardships of divorce.
The gang attempts to find adventure on the sea after they purchase their 'new' boat.
Mac finally gets his big break after correctly answering a trivia question on the radio. While Frank, Dennis, and Dee take their bar-banter to the internet with their own podcast.
Rejected from a pool club, Mac and Charlie set out fix an abandoned pool to help cope with the Philly heat wave. Meanwhile, Dennis and Dee go about dealing with the heat in a different way.
Mac's mother is left homeless after she burns down her house, which leaves Charlie and Mac with no choice but to make new living arrangements; when Dee feels under the weather, Frank tries to muster his paternal instincts to care for her.
The gang gets a real scare after Dee reveals she's pregnant, forcing the guys to recall their last hazy Halloween party to determine who the father is.
A blast from the past prompts the guys to expand membership, and Dee to re-consider her future.
Motivated by the drama teacher who inspired her, Dee takes a job as a substitute teacher, and exposes her students to the culture of Paddy's with a field trip to see the Gang's take on the Lethal Weapon series: Lethal Weapon 5.
Keeping the basement rodent-free drives Charlie to the brink. The gang throws Charlie a surprise party.
En route to Atlantic City for a charity event, Mac, Frank and Dee get lost. Meanwhile, Dennis and Charlie hitch a ride to town.
Dee's blessed event is fast approaching but the father's identity remains a mystery---to the gang, at least. So they throw a party and invite all of Dee's former flings.
After years of being mistreated by Frank during the holiday season, Dennis and Dee decide to teach him a lesson. Meanwhile, Mac and Charlie reflect on their childhood Christmases, and realize that they were not as joyous and wonderful as they remembered.