Transcript for Would You Fall For That? Marry a Stranger
we are cordially inviting you to the wedding of the century. We shall begin. Yep, that is me, pretending to be the officiant at a wedding. We're gathered today on this special dale with this special couple. And yes, that is my colleague sasheer, pretending she's a bride. Acting her socks off, pretending she's in love with our man scott, playing the tearful groom. You've done it by being yourself. Perhaps after all, that's what being a friend means. And here's the plan. We're going to invite a random, unwitting member of the public to act as the witness to scott and sasheer's fake wedding. Then, using psychological principles, try to get that witness to exchange vows with scott. All right, so, this is a totally extreme test of social conformity and authority. Yeah, I think get the authority part. Because you look like a judge, you sound like a judge. We might just believe you and just do whatever you say. Yeah and because we're all acting like nothing weird is happening, we're encouraging people to conform. Absolutely. And it's the most extreme experiment we've come up with so far, because we are going to try to make somebody marry a stranger. Don't get much stranger than this. For our experiment, we've taken over a real church with cameras perched high above the street outside. And inside, cameras hidden in nooks and crannies, controlled from a secret lair behind that door. Before getting started, we had our own version of a wedding rehearsal. Witness that I -- we scoured the internet to find something lovely and romantic that scott should read to sasheer. I love you not only for what you are, but for what I am when I'm with you. You know, just to get our unwitting passer by comfortable to give them a little time to settle in to the process. I'm sorry. I didn't mean to make you more nervous. I would told to base my performance on rowan atkinson from "four weddings and a funeral." May god bless you all. The father, the son and the holy sp spirit. We. Reporter: Ready to go. Scott and sasheer hit the sidewalk looking for our victim -- I mean, I mean our test subject. Not an easy task. Excuse me? Hi, sorry, are you in a rush? Yes. Oh, okay. Excuse me, hi, we're -- we're trying to get married. Then sasheer stops a lady called kathleen. Excuse me. Hi, sorry to bother you. We're getting married right now and our witness didn't show up. The church won't let us stay -- yeah, we got to be out of here soon. After ten minutes. We just need someone to stand there quickly and act like you know us. Kathleen has taken the bait and believes she agreed to be the witness at sasheer and scott's wedding. But as she enters the church, she has absolutely no idea that we plan to turn her walk down the sidewalk into a walk down the aisle. Hi, my name is nick. I'm the officiant today. Kathleen. Kathleen, lovely to meet you. Mr. Adams, I'll just take your name, if you don't mind. It's kathleen with a "c"? No, with a "k." With a "k." I'm a little bit new to this game, so bear with me. Love weddings, but I'm not very good at them. I'm a bundle of nerves. She seems so sweet. And sharp. Surely she's not going to fall for it. She's going to tell me I'm an idiot, to get out of her face. She'll storm out. Scott and sasheer, it's my duty now to remind you of the solemn and binding character of the ceremony of marriage, which brings you together for life. Kathleen, if I could ask you to repeat after me. I am witnessing here today -- I am witnessing here today -- so far so good. I'm in control. She's obeying the reasonable requests. She's agreed to witness the wedding. No big deal. Then scott launches into that tear-jerker of a reading. Remember, the one we found on the internet. I love you because you've done more than any creed could have done to make me good. Look at kathleen's face. She's enjoying scott's soppiness. The reading is working far better than we ever hoped. It's sweet, and kathleen is becoming emotionally invested in what's going on. Perhaps after all, that's what being a friend means. I love you. I love you, too. We've softened her up. But I'm petrified on the inside, calm on the outside. I'm about to turn the tables. Will kathleen actually marry scott? Surely, surely not. Remember, she's a random passer-by. She's never met any of us before. Just five minutes before, she was walking along the street, minding her own business. I do solemnly declare. I do solemnly declare. That I know not -- that I know not -- of any lawful impediment. Of any lawful impediment. Why i. Why i. May not be joined. May not be joined. In matrimony. In matrimony. Yes, she really did just say there's no legal reason why she can't get married. Okay, that's a bit weird that we're asking the witness that question. She looks at mr. Adams, the registrar, seemingly looking for help. Someone to agree with her that this is a bit weird. But he's with us, he's our producer, and like the rest of us, he is acting like nothing weird is happening. So kathleen continues on. Do you have the ring? Good grief, it's working. Okay, we're going deeper, we're going further. We're going to see how far we can get to her marrying mr. Scott rogowsky. A man she's never met. Here we go. It's time for the rings. When we come back -- the ring? And again, repeat after me.
This transcript has been automatically generated and may not be 100% accurate.