The fifth season of It's Always Sunny in Philadelphia, premiered on FX on September 17, 2009. The season contains 12 episodes and concluded airing on December 10, 2009.
Dennis, Mac, and Frank go into real estate, while Dee sets out to be a surrogate for a wealthy couple. Charlie gets into it with an attorney over the law.
The gang tries to expand their horizons by going on a road trip to the Grand Canyon.
With a shantytown taking shape outside, Mac and Dennis try to keep Paddy's going in tough times. Meanwhile, Frank and Dee start a family business.
Frank's behavior is more bizarre than usual---so bizarre that even the gang notice---so they decide to stage an intervention.
The waitress is getting married, Dee is jealous that she's beating her to the altar, so she tries to derail the wedding.
The gang describes the trials and tribulations they went through, during game five of the World Series, in hopes the judge will clear them of all the citations they received.
The gang puts together a wrestling show for returning troops. Meanwhile, Dee finally meets the soldier that she has been communicating with over the internet.
The gang decides to expand their business by developing a number of products that they could sell at Paddy's pub.
Mac and Dennis decide that they need to spend some time away from each other. Meanwhile, Charlie helps Dee search for her cat.
Dennis reveals his foolproof system for seducing any woman to the rest of the gang, but they don't grasp the concept.
When Dee gets a part in the new M. Night Shyamalan film, Mac and Charlie seize a chance to pitch their movie script.
After being banned for 10 years from a local drinking competition appropriately named "Flipadelphia," the gang tries to reignite their old rivalry with another local bar. Finding that they are in need of some serious practice, the guys head to Dennis' old fraternity house at the University of Pennsylvania to get their game up to speed while Dee hones her skills on her own. Frank wears skinny pants.