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Whenever Sean Hayes and Kristin Chenoweth wrap up their run in Promises, Promises, someone should build a sitcom around the Emmy-winning stars. We know they're both funny in their own right: Anyone who saw Hayes as the flamboyantly out-and-proud Jack on "Will & Grace" or Chenoweth pining for the pie-maker on the sweet dramedy "Pushing Daisies" can vouch for that. But together, they exude an inimitable fizzy chemistry — the kind you want to bottle and dole out in 22-minute must-see weekly doses.

HAYES: Yesterday, I saw this "Oprah" thing.

CHENOWETH: I watched it last night!

HAYES: Isn't that crazy? Where they make people's legs longer in China?

CHENOWETH: I went, "Where do I sign up!?!" HAYES: They break the bone, and separate [it] and hold the rest in place with a metal thing.

CHENOWETH: If I'd have only known that when I was younger! I would have been like, "Yo, parents! Break it!"

Currently, the duo is cracking wise at the Broadway Theatre in a revival of the ever-so-cynical '60s musical Promises, Promises, the Neil Simon/Burt Bacharach/Hal David hit inspired by Billy Wilder's office-politics-and-adultery film "The Apartment." Hayes plays inconspicuous worker bee Chuck Baxter, who has his eye on "this real pretty girl who works up in the employees' cafeteria, Fran Kubelik" (Chenoweth). But she's a little busy getting busy with Baxter's married boss Sheldrake ("Ghost" star Tony Goldwyn)…frequently in Baxter's apartment. Oh, yes — did we mention that Baxter lends out his West 67th Street one-bedroom to philandering co-workers who possess the power to promote him?

HAYES: A question I get a lot is, "So, are you guys updating it?" No...it takes place in 1962, actually! There's nothing 2010 about it.

CHENOWETH: But the issues that they're fighting within themselves still exist.

HAYES: Infidelities, untruths…you will watch it and go, "Oh, completely been there."

CHENOWETH: I don't think there's a woman alive who hasn't been in love with the wrong man, and who can't see Mr. Wonderful right in front of her. I'm of a certain age and I'm not married.

HAYES: Yet. Wait till I get down on my knee!

CHENOWETH: I can't wait — you know I'll say yes! Do it at the curtain call. We'll get more publicity.

The eight-show-a-week grind, the stage-door autograph hounds, the dietary sacrifices a singer makes for a phlegm-free throat (so long, ice cream!) — it’s all new to Hayes, who's making his Broadway debut. He describes his run in 2008's Damn Yankees at City Center as "a nice little handshake to New York. I'm saying, 'Hello, and I'll be on my way. I won't interfere with your establishment as of yet.'" Chenoweth, meanwhile, ranks as one of the theatre's most bankable stars — a Tony winner, and Wicked's original and undoubtedly most popular Glinda. She got her first taste of Promises as a college student in her native Oklahoma: "I was 19. I looked like I was 12. I was like, 'I guess she fell in love with a married man, shame on her! And then she doesn't like him?’ [pointing to Baxter] Why not? Crazy! Okay, I'll act!'” She sighs. "It was summer stock. I also had Tuptim in The King and I. Another role I was perfect for." Yet she insists that Hayes needed none of her counsel; rather, it was she who relied on her less experienced co-star's assistance.

CHENOWETH: I went over to his apartment the night before they offered me the role.

HAYES: And she got it! Which is weird.

Okay, in all seriousness…

CHENOWETH: He doesn't need my advice.

HAYES: Oh please, I'm constantly asking her — the first day, she brought me a huge bag from Duane Reade of 50,000 products to keep yourself healthy.

CHENOWETH: And of course I got sick!

HAYES: Just the other day I asked her, "Am I singing correctly?"

CHENOWETH: He just needs to be his darling self, which is perfect. But I am going to make him wear gloves when he goes out and [greets fans]. Your whole thinking changes when you're on Broadway. You wake up and you're like, "There's a tickle, my glands are swollen. [Vocalizing] Hmm, hmm…okay, I’m good."

HAYES: That's why I do a steam shower every day.

CHENOWETH: Steam, nasal douche, the whole thing. I also never go out unless I absolutely have to. I don't really have an exciting life.

HAYES:­ And that's me when I'm not doing Broadway, by the way.

CHENOWETH: That's why we get along so well. We're both homebodies. I honestly feel like we were separated at birth.

"Separated at Birth." A potential sitcom title, perhaps?