Article continues below advertisementCharlie Day is looking forward to filming It's Always Sunny in Philadelphia. The actor speaks exclusively with OK! about the beloved series, launching Four Walls Whiskey with his castmates and hosting tasting events in Boston. Article continues below advertisementThe Return of 'It's Always Sunny in Philadelphia' Source: MEGA Charlie Day says Season 17 of 'It's Always Sunny in Philadelphia' was the show's 'best' season.