Someone's Coming On to Your Mate: What Would You Do?

Has anyone ever hit on your spouse or significant other?

The 'waitress' at this romantic restaurant is actually an actress who was asked to flirt with Niki's boyfriend, Drew, as part of an ABC News hidden camera experiment.

(ABC News)

ABC News wanted to see what people in relationships would do if they saw a stranger flirting with their loved one.

So far, the hidden camera experiment has elicited reactions ranging from good humor to direct confrontation.

And in this latest experiment, rage.

'It's Gonna Be a Long Night'

We set up the experiment at Ennio & Michael's restaurant, a cozy Italian bistro in New York's Greenwich Village. A beautiful actor named Jessie played the flirtatious waitress.

Nobody would have guessed that the first target -- sweet-looking Nikki -- would react in a more aggressive way than all of the participants combined, both male and female.

As soon as Nikki and her boyfriend -- who was in on the plot -- sat down to dinner, Nikki immediately noticed Jessie showering him with unwanted advances.

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Then, as Jessie lightly touched Drew while taking his drink order, Nikki's anger began to surface.

"It's gonna be a long night," Nikki said sarcastically. She told Drew not to think she didn't notice the waitress' touch.

'I'm Gonna ... Rip Her Fingernails Out'

When Jessie came back with the drink order, she told Drew she made the Jack on the Rocks especially for him. Nikki had had it.

Speaking to Drew, she cursed like a sailor about Jessie.

"I hope you like all the hair on your head," she said. "You better shut the f-- up now because I'm gonna rip it out! I'll beat the s-- out of her if she tries to take my man."

Nikki also jokingly planned her vengeance. "I'm going to have to kill her now, you know that, right?"

Drew asked her to wait until after dinner. Even Drew acted as if he were a little worried. He half-jokingly asked whether he should take her knife away from her.

To diffuse the situation, Drew and Nikki shared a kiss even as Jessie came back and began to hit on Nikki's man even more aggressively.

As Jessie spoke to them about the menu, she placed her hand on Drew's shoulder. She then walked away from Nikki's glaring eyes and Nikki laughed ominously.

"I'm gonna f--ing rip her fingernails out of her f--ing fingertips," Nikki said.