ALL NEW "WHAT WOULD YOU DO?" SCENARIOS LOOK AT HOW PEOPLE REACT TO ETHICAL DILEMMAS, ON "20/20," FRIDAY, APRIL 25 ON ABC

Plus: John Stossel Interviews Arianna Huffington

Imagine strangers seeing a lost child on a busy street... would they stop to help? This Friday's "20/20" features four scenarios from the "Primetime: What Would You Do?" limited series. Using hidden cameras, the show sets up everyday situations and captures people's reactions. Whether people are compelled to act or mind their own business, John Qui�ones reports on their split-second - and often surprising - decision-making process. "20/20" airs FRIDAY, APRIL 25 (10:00-11:00 p.m., ET) on the ABC Television Network. Also, John Stossel interviews political mover and shaker Arianna Huffington

Friday's "What Would You Do?" scenarios include:

* Lost Child: When a young child appears to be lost on a busy street, will people passing by do anything to intervene?

* Gay PDA: Are public displays of affection appropriate for anyone? And what happens when the romantic couples are gay men and women?

* Idol Wannabe: People love to watch the train wreck auditions of off-key singers on "American Idol." But how truthful will people be when faced directly with awful singers? Will they keep their opinions to themselves or speak up?

* Stranger Flirtation: How will an older couple react to unwanted flirtation from a waiter hitting on their significant other?

And: John Stossel interviews Arianna Huffington about her political transformation and confronts her about her opinion that government programs are the solution to society's problems. In her new book, Right is Wrong, Huffington argues that the "lunatic fringe" of American conservatism has "hijacked" the country, and her website seems to count John Stossel among this class of extreme right-wingers. Stossel and Huffington spar over the presidential election and just how "big" government should be.

David Sloan is the executive producer of "20/20."