When reality bites -- and cries and spits up

For reasons probably best explored in a therapist's office, there's nothing quite so satisfying as watching young children misbehave on television. Put a few lively kids and a bowl of spaghetti and meatballs in a room together and who among us can watch without a horrified chuckle? Especially when their parents are ineffectually present, shouting idle threats or just rocking in a corner, emitting the occasional whimper.

From "Kids Say the Darndest Things" to "Supernanny" and "Living Lohan," the antics of other people's children, and by extension, the flaws of other people's parenting, offer seemingly limitless entertainment value.

So "The Baby Borrowers," which premieres tonight on NBC, seems somewhat inevitable. Based on a British show of similar construct, it installs five teenage couples who think they're ready for marriage and children in a suburban cul-de-sac and hands them a succession of people to care for -- infants, toddlers, tweens, teens and finally, aged parental types, with their pillboxes and physical limitations. (Not to worry, the real parents are just a few houses away, monitoring via video and able to intervene if they feel things get out of hand.)

It is not a competition -- there is no cash incentive and no one is voted off the cul-de-sac. The prize appears to be, oddly enough, wisdom. At the end of their weeks-long experiment, the participants hope to know more about themselves as couples and potential parents.

So let the howling and projectile vomiting begin. Which it does, resulting in a blend of "The Hills" and "Nanny 911," crossed with a public service announcement against teen pregnancy.

By turns touching and exasperating, "The Baby Borrowers" seems at first to be the ultimate parental revenge fantasy -- we'll show those know-it-all-teens what it means to be adult. But it winds up surprisingly nuanced. Sure, there's emotional comeuppance galore, but "The Baby Borrowers" also quickly makes it clear that it's just as difficult to be 18 as it is to be a parent. Which is why the two, perhaps, should not coincide.

With requisite geographic, racial and class diversity, the five couples share one thing -- the belief that they are ready to get on with it. That belief is not completely universal -- Sean and Kelsey entered this experiment with opposing agendas. Kelsey wants to prove that they're ready to become a family, and Sean wants her to stand down for a while. Cory and Alicea believe that young parents have a more instant empathy with children. The others -- Austin and Kelly, Jordan and Sasha, and Daton and Morgan -- are hoping to prove themselves as responsible adults and see if their relationships are heading toward marriage.