Neal Justin: 'It's Always Sunny in Philadelphia' should consider calling it quits

"The Simpsons" just aired its 750th episode. "South Park" has produced over 300. "It's Always Sunny in Philadelphia" has only churned out 162 episodes, but in some ways, its longevity is even more impressive.

That's because the series is a live-action sitcom, limiting the amount of adventures and story lines it can explore. The only other show of its kind to last this long was "The Adventures of Ozzie and Harriet," a snooze-fest about a family that made the Bradys look like wild hippies.

The characters in "Sunny," who run an Irish pub that has somehow managed to avoid being shut down by health inspectors, are the polar opposites of Ozzie and Harriet Nelson. The pub owners' idea of a family dinner is a food fight in a strip joint.

It has been a zany, unpredictable and creative run. And now it's time to stop the madness.

It's not that the writers and cast members have run out of bad behavior. The 16th season, which kicks off at 9 p.m. Wednesday on FXX and streaming on Hulu Thursday, is full of naughtiness.

In the first six episodes, we snicker as the gang invests in inflatable furniture, hunts down a jar of rotting teeth and lusts over animatronic characters in a Chuck E. Cheese-like restaurant. At one point, they kidnap "Breaking Bad" stars Bryan Cranston and Aaron Paul in an ill-fated attempt to pitch their own alcohol brand.

The cast is still in top form. Rob McElhenney, who plays the hopeless but hapless romantic Mac, has a nice running bit in the season premiere in which his face slowly inflates from a nut allergy. McElhenney, who also co-created the series, is fully committed to looking ridiculous. That's nothing new. He packed on 60 pounds for the seventh season, just to add a new twist.

Charlie Day, who has spent his off seasons standing out in movies like "Horrible Bosses," continues to find ways to explore the eccentricities of his character, Charlie. We learn in an upcoming episode that he'd rather urinate in a pail than use his apartment's bathroom.

The show's not-so-secret weapon is Danny DeVito, who joined the cast in the second season. His Frank is slightly smarter and silghtly more digusting than the others. This year, he accidentally shoots his niece and nephew, then acts like he did nothing more inappropriate than pass gas in an elevator. He also beats a seagull to death.

Scenes like these once had us gasping for air. Not anymore. There's nothing short of the gang triggering a nuclear war that would startle longtime viewers.

Now that the shock value has greatly diminished, so have the reasons to tune in every week. The same could be said of "South Park." I once admired the show for its sheer nerve. But I can't remember the last time I actually watched a new episode.

FXX isn't ready to give up on its signature show. It has renewed the sitcom for two more seasons after this one. But will it actually last that long?

On the "Smartless" podcast last year, Day hinted that this batch of eight episodes might be the last.

"We've done a lot of these. I don't know how long we can keep them up," he said. "When we were shooting that pilot, I was 27 years old. I'm 46, so I feel like I've put in my time with this one."

Day may play dumb on screen, but he's suggesting something smart: It's time to move on while the sun is still shining.