Feb. 26, 2008 -- Would you tell your good friend if you saw his or her significant other canoodling with a complete stranger?
ABC News recruited six couples and asked them to pretend to cheat on their mate in front of an unsuspecting best friend.
We set up our experiment at an Italian restaurant in New York's Greenwich Village rigged with hidden cameras.
In our first experiment we watched as Kylie witnessed her best friend's boyfriend entwined with another woman — and bravely broke the news to her friend Mary Ellen.
But what if the cheater is a woman engaged to be married? And suppose the guy who is about to catch her in the act is the best man in her wedding?
Jay Reyes was the "best man to be" at Kyong — a.k.a. Kookie — Ko and Carmelo Vasquez' wedding. He was brought to the restaurant by his wife, Carolyn Foster. Carolyn was in on the experiment and so were the bride and groom. Kookie, the bride, became cozy with the stranger — an actor hired by ABC News. Jay had no idea it was all an experiment and that hidden cameras were rolling.
Before the experiment began, we asked the engaged couple what thought Jay would do, including what they would think if he didn't say anything. "Oh, then you'll have to cut your cameras," Carmelo joked, admitting he would be a bit upset if Jay did not tell him.
It took 10 minutes for Jay to spot the cheating bride-to-be canoodling with our actor. Jay peered through a mirror on a nearby wall and panicked.
"Oh my God," Jay exclaimed. "What do I do? Oh my God."
Again, we added a twist. Jay' best friend Carmelo — who was being cheated on — made plans to join him for dinner at that very restaurant. Carmelo would arrive at the restaurant at any moment, increasing the stakes for disaster. Jay decided to send him a text message asking if he knew of Kookie's whereabouts.
Since Carmelo was in on the experiment, he responded by saying that his fiance had to take care of something after work. Jay looked up from his text and shuddered at the sight of our actor playing with Kookie's hair. When Jay assumed Carmelo was just blocks away, a look of horror crossed his face. He turned to his wife and said that if he were the one being cheated on, he would want somebody to tell him.
Through an earpiece, we told Kookie and our actor to get the check and head for the door, right past Jay's table.
Kyong paused to say hello and introduced our actor as a coworker. Jay told her he would see her later and asked her to give Carmelo his regards.
After they left, Jay confided to his wife that his stomach was in knots and it was all he could think about. He inhaled breadsticks, one after the other, in anticipation of his best friend's arrival.
Jay's wife told him it was up to him to tell Carmelo. The moment of decision quickly arrived as the groom-to-be walked through the door. "I'm going to give you an option, I'm going to lay it flat out," Jay said. "You're my best friend — I love you — I would do anything for you in this world, anything."
"What's the matter," Carmelo asked. "You guys all right?"
Jay said he was fine, but asked Carmelo to give him some time. He suggested talking after dinner, when they could have a more personal discussion. Jay suggested waiting until the next day.
Carmelo told Jay that if there was something he needed to tell him, he must say it immediately. Jay stalled with a few sips of wine. He attempted to change the subject. We wondered if Jay would come clean with his wife steps away. To find out, we told Carolyn to go to the ladies room. "You're going to throw me right into the sharks," Jay calls after her. "Are you kidding me?" Finally, Jay pulled the trigger. He told Carmelo he saw his fiancé in the restaurant having dinner with a co-worker and that she left a few seconds before he arrived. Carmelo asked Jay if he was being serious. Jay said he was dead serious. Carmelo asked him if he was sure it was Kookie.
Jay said he saw the coworker, Brian, holding her hand the whole time and feeding her. Then Jay suggested Kookie might have cold feet.
"People that flirt around with other people, they hang out with other people because they know they're going to get married and they do stupid s***," he said. "They, they test themselves to see if this is what they really want. I had a pit in my stomach buddy, so everything in my body was telling me it was wrong."
But suddenly the mood changed as Jay confided a secret to his buddy. "I made a mistake at one point in my life," he said. "In the relationship, I really couldn't convey what I wanted to say."
Afterwards, Jay warned Carmelo not to make the same mistake. "You do not call her a whore, you do not call her a slut or bitch," he said. By referencing his own mistake, he suggested that if Carmelo really loved Kookie he must listen to her and not push her into another man's arms.
"Give it a fight," Jay said. "Give it a fair fight and don't push that person away even further."
Jay's wife returned to the table and we decided it was time to end Jay's ordeal. Our correspondent arrived and told him he was part of a scenario on cheating. Jay said he had no choice but to speak up for his best friend of fourteen years.
"It's a unity, it's one person. It's a person, it's two people who supposedly become one," he said. "That bond's supposed to be stronger than anything . I couldn't let him make a bond with someone who wasn't going to do that."
"I think he gave him excellent advice," said Donna Barnes, a life and relationship coach who watched the scenario unforld with ABC News producers. "You know, he's just kind of going, 'Hey look, you need to handle this delicately and figure out what's going on.'"
Maybe, but Carmelo had better be ready for some serious payback from his best man. It turned out this was not the first time Jay had been the target of one of his buddy's pranks. On New Year's Eve, Carmelo took a razor to Jay's eyebrow while he was asleep.