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 pulls out the big guns to protect the sanctity of marriage, while the rest of the gang reap the rewards of marital bliss.
Marital bliss turns to marital business, as the gang experiences the emotional and economic tribulations of divorce.
The gang attempts to open themselves up to the adventures of 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.
After getting denied from the local pool club, Mac and Charlie aim to fix up an abandoned pool in order to beat the heat wave. Meanwhile, Dennis and Dee try to beat the heat in a more 'dignified' and 'upper-class' way.
Charlie and Mac set-up a truly odd couple after Mac's Mom burns the house down, while Frank discovers the importance of paternal care when Dee falls ill.
The gang gets a real 'scare' after Dee reveals she's pregnant, forcing the guys to recall their last hazy Halloween Party to determine if one of them might be the father.
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.
When keeping the basement rodent-free drives Charlie to the brink, the gang decides to put the cynicism aside and throw a surprise party to cheer him up.
Things go awry as the Gang travels to Atlantic City for a charity benefit. While Frank, Dee and Mac try to survive in the woods, Dennis and Charlie hitch a ride to the city and have the night of their lives.
Before Dee's baby arrives, the Gang tries to figure out who is the father by throwing a house party for all her former flings.
Ho, ho, heyooo! Christmas is upon us and the Paddy's gang has got the spirit. Well, not really. For them, the holidays have always been a time of trickery, backstabbing, and disappointment. But this year things are going to be different as they are determined to rediscover the joy in Christmas. Join Mac, Charlie, Dennis, Dee and Frank as they embark on a holiday adventure filled with stolen toys, childhood videos, naked elves, and a bloody run in with Santa Claus.