The first season of the American television sitcom series It's Always Sunny in Philadelphia premiered on FX on August 4, 2005.

This season, the gang inadvertently turns Paddy's Pub into a gay bar after one of Sweet Dee's acting class members invites his gay friends over to drink while Mac and Charlie try to prove to Charlie's crush that they are not prejudiced against African Americans.

The gang then turns their bar into a safe haven for underage drinkers—and find themselves regressing to their high school ways when they get invited to the prom.

Following that, the gang finds a dead man in one of their booths and Dee and Dennis visit their ailing (Nazi) grandfather at a nursing home.

The website's critical consensus reads, "It's Always Sunny in Philadelphia's coarse humor and shabby style may be rough around the edges, but this sinful sitcom wrings a surprising amount [of] charm from its band of charmless underachievers.