The gang from Paddy’s Pub is back for more demented shenanigans when “It’s Always Sunny in Philadelphia” returns to FX tomorrow night. Of course, if you had told me back in 2005 that the comedy series would even make it to a sixth season, I probably wouldn’t have believed you, because while the show has always been funny to a certain degree, it wasn’t until around Season Three (a year after executive producer Danny DeVito joined the cast) that it really began to find its groove. I’ve also always been surprised to learn how many people watch the show considering its un-PC brand of humor, but the numbers don’t lie – “It’s Always Sunny” continues to grow in viewership every year, conceivably because fans are getting their friends hooked in the same way that many found out about the show themselves.

After what was arguably their most successful season to date (thanks to episodes like “The World Series Defense,” “The D.E.N.N.I.S. System” and “The Gang Reignites the Rivalry”), fans will be happy to learn that Season Six is just as perversely funny as before. Though they had to work actress Kaitlin Olson’s real-life pregnancy into the story this year, they’ve done so in a way that doesn’t feel cheap. In the aptly titled season premiere, “Who Got Dee Pregnant?,” we discover that the gang’s lone female member not only has a bun in the oven, but that one of the guys might be the father.

The rest of the episode revolves around Dennis, Mac, Charlie and Frank recalling the night of conception (a booze-filled Halloween party with plenty of twists and alternate versions of the story) in order to figure out which one of them is the father. I won’t ruin it for you here, but I will say that they definitely throw you for a loop after messing with your mind in true “It’s Always Sunny” fashion. Check out the video below for more about the season premiere, and then tune in tomorrow night for the answer.