Reporter Charlie LeDuff spends quality time with a number of curious subcultures in the new series “Only in America” (9 p.m., Discovery Times). Of course, it depends on how you define quality time.

LeDuff’s first assignment is to become a familiar face around the East Bay Rats, an Oakland, Calif., club that sponsors a weekly “fight club.” Determined to fit in, LeDuff challenges the biggest and scariest Rat to meet him in the ring, where, presumably, he will turn LeDuff’s familiar face into strawberry jelly. But as he prepares for his big bout, LeDuff discovers that his challenger and most of the Rats have personal complexities that run deeper than their tattoos.

As LeDuff theorizes, the Rats are children of divorce or families dissolved by drugs and alcohol. In a world where words like “honor” and “loyalty” seem like empty slogans, their allegiance to their brother club members becomes the most profound commitment in their lives.

But does LeDuff actually have to get his face pummeled to figure that out? Is this reporting, or spectacle? George Plimpton did similar things some four decades back when he suited-up with the Detroit Lions and wrote “Paper Lion.” And, of course, that made George Plimpton a star.

Next week, LeDuff decamps for Oklahoma City to discover the world of gay rodeos. After that, it’s on to Amarillo, Texas, and the grueling life in the Arena Football League.

Today’s other highlights

¢ The Encore Channel celebrates the era of Ronald Reagan, the Brat Pack, big hair and shoulder pads with an 80-movie Labor Day ’80s marathon, beginning tonight with “The Karate Kid” (7 p.m., Encore). On hand to celebrate the decade are original MTV VJs Nina Blackwood, Mark Goodman and Alan Hunter.

¢ “Dateline” (7 p.m., NBC) engages in a little nostalgia of its own, glancing back at the tabloid case of the 1990s, the notorious trial of O.J. Simpson. It has been nearly 10 years since the seemingly endless trial reached its conclusion. And “Dateline” is not alone – “Frontline” looks back at the O.J. verdict on Oct. 4th, the 10th anniversary of the Juice’s acquittal.

¢ On two episodes of “Arrested Development” (Fox) Ben Stiller (8 p.m.), Ann leads a censorious boycott (8:30 p.m.).

¢ A bus breakdown aids a prison break on “Numb3rs” (10 p.m., CBS)