WHAT'S UP, DOCS?

There's a new tradition on the "Scrubs" set in its second season: a weekly challenge called "Scrubs Factor." In its first installment, cast and crew members were offered $100 for every pickled pig's foot they could eat. (An assistant director took home the loot, after chomping down seven feet.) Then there are the standing wagers outside of this tourney, like the open challenge for anyone to spend an hour in a drawer in the basement's morgue. (The medical comedy is written, shot, and edited in a Studio City hospital that was closed in 1998.) "I hate turning down bets, but that was like, there's no way," says Sarah Chalke, who plays the driven, social-skills-free Elliot. "There's still mung in the trays."

The biggest "Scrubs" gamble, however, comes courtesy of NBC, which handed the sophomore comedy the hallowed post-"Friends" time slot. That makes it the first critically acclaimed show to start the season Thursdays at 8:30 since, well, "Friends" did in 1994. "The spotlight is so bright [at 8:30], it's almost unfair to ask any new show to go in, no matter how good it is," says NBC Entertainment president Jeff Zucker. (Feel free to snicker when mentally pairing the word "good" with slot alums ranging from "The Single Guy" to "Inside Schwartz.") "We realized we would probably be better serving the time period and ourselves if we moved an established show in there."

This increasingly rare instance of a network heartily supporting a show that hasn't yet reached smash status (it finished in 38th place last year) has the cast somewhat mystified. Says Judy Reyes (the no-nonsense nurse Carla), "Jeff Zucker loves himself some 'Scrubs,' I have to say." So far the prognosis seems positive: Since "Scrubs" moved into its new time slot this summer, it has been retaining 87 percent of "Friends"' audience -- and Zucker has been quoted as saying that he'll be happy with a 70 percent retention when "Survivor" returns. "I cut that [article] out so I could fax it over to him every time the numbers come out," laughs show creator and executive producer Bill Lawrence.

Being bequeathed TV's highest-profile -- and, some would say, most cursed -- time slot hasn't given the cast a case of nerves. In fact, they're downright Zen about it. Visit the set and you're likely to see John C. McGinley (the unrelentingly sarcastic Dr. Cox) practicing Rollerblading in the hall. Between shots, Faison's been known to strum a guitar and perform his impression of Neil Diamond singing the theme from the cartoon "Transformers." Things are so relaxed that when the actors finish early, they often won't leave. "People hang out because they're laughing so hard they don't want to go home," says Zach Braff, who stars as the show's hapless protagonist, the eager resident J.D. Credit for this chummy atmosphere is given to Lawrence's strict "no a--hole" policy, announced at the beginning of last season. "I would rather have a good guy than an a--hole who's slightly better at a job," he says. "It's a quality-of-life thing."

Lawrence extends the show's collegiality by hiring friends and loved ones for guest shots. The upcoming season is no exception: His real-life wife, Christa Miller ("The Drew Carey Show"), will be back for repeated appearances as Cox's witchy ex, as will Heather Locklear (Lawrence cocreated "Spin City"), guesting as a horny pharmaceutical rep. Schedule permitting, pal Brendan Fraser will reprise his role as a leukemia patient. Since many fans and critics noted how much Braff looked like "Ed"'s Tom Cavanagh, this Halloween Cavanagh will guest-star as J.D.'s older brother. And after Braff turned Lawrence on to former Men at Work frontman Colin Hay's solo career, he made Hay the show's unofficial troubadour: Not only does he appear in the season premiere, but two of Hay's songs will be on the "Scrubs" soundtrack (in stores Sept. 24).

One thing "Scrubs" will not do is pair off J.D. and Elliot. After a brief one-episode dalliance last season, Lawrence decided to end the affair and concentrate on only one couple, Turk and Carla (who are headed for a proposal this year). Leaving the will-they/won't-they chestnut to lead-ins Ross and Rachel, Lawrence's plan for J.D. and Elliot is that "once a year, without any warning, they'll randomly f---. And it always falls apart the very next day.... That feels real to me."

Speaking of reality checks, here's one: The utopian feel on the set is easy to maintain before the season starts -- but what if "Scrubs" becomes a true Must See "Friends"-level cultural phenomenon? In that stratosphere, can a newly all-star cast keep from becoming a--holes? "It took me a long time to get here," says Faison ("Clueless"). "I wasn't an a--hole when I got here, so I'm not gonna become an a--hole.... You control your a--holeness." Actually, that's a damn good prescription for celebrities in general.