Rob McElhenney, Charlie Day and Glenn Howerton do such a convincing job of portraying a trio of degenerate, sex-crazed narcissists that it's hard to believe "It's Always Sunny in Philadelphia" is set to begin its third season on FX Thursday.

How could these hedonistic slackers pull themselves together long enough to produce 15 half-hour segs of a single-camera show on which they all serve as genuine multihyphenates -- stars, writers, producers and, in the case of McElhenney, an occasional helmer.

Perhaps it was all that real-life unemployment that the three endured just a few years ago when they were struggling actors yearning to eat regularly. Since its 2005 debut on FX, "Sunny" has become the poster child for the groundswell in the biz of actors taking matters into their own hands and writing their own material, on the theory that it can't be any worse than the crap they're being turned down for anyway.

"I jumped from waiting tables in West Hollywood one night to directing a pilot and showrunning," McElhenney still marvels, even with 34 episodes (and counting) under his belt. "It's such a great complement when people say (the threesome) come off as a comedy troupe that has been working together for years. Because we haven't. We were friends before, but we never worked together."

Click here for clips of the new "Sunny" segs on the FX website, or check out the promo vids posted below.

(Pictured above, from left: Glenn Howerton, Rob McElhenney and Charlie Day)

WARNING: VID POSTED BELOW IS NOT EXACTLY FAMILY-FRIENDLY

You've gotta give Danny DeVito credit for lending his considerable charm to FX's "It's Always Sunny in Philadelphia." At this stage in his career, a sitcom supporting role is hardly something he needs, but by all accounts DeVito loves the show and the creative forces behind it, namely creator/stars Rob McElhenney, Charlie Day and Glenn Howerton.

However, the truth is now emerging about another reason (let's just say it involves Vaseline) why he's been so willing to toil in basic-cable land. There's a certain third-season stipulation in DeVito's contract, as documented in this clever bit of viral marketing posted on Will Ferrell's FunnyorDie.com site. Even Rhea Perlman gets into the act. The humor on "Sunny" generally goes pretty far, but I think this one's a little randy even for them, which makes it perfect for the a bit of viral marketing to tubthump for the show's Sept. 13 preem.