Time for a preview of our "what would you do?" John quinones gets to the bottom of this one. We're back. And it's a disturbing trend. In order to get their boyfriends to propose, some women will fake... See More
Time for a preview of our "what would you do?" John quinones gets to the bottom of this one. We're back. And it's a disturbing trend. In order to get their boyfriends to propose, some women will fake their pregnancy. They'll buy a positive pregnancy test from a woman who is really expecting a child. Then, they try to pass that test off as their own. "What would you do?" If you witnessed the whole thing? Would you say anything? And most importantly, would you tell the boyfriend he's being deceived? I have a pregnancy test here for $25. Reporter: If you saw this transaction. We're pregnant. Reporter: And this deception -- "what would you do?" One pregnancy test I took this morning, has a positive sign on it, $25. Check that out. Reporter: She's so captivated, she barely looks down. Boyfriend's coming in. How are you? How are you? Good. I have big, big, big news. What is it? We're pregnant. Oh, wow. Here's the test. Officially. You don't seem excited. Well, are you sure these are accurate? Well, you know what? I have more. I will go take another one, okay? Reporter: Eric is left alone. As they keep to themselves, he becomes desperate for another woman's advice. Excuse me, guys. Sorry to rupt. I'm freaking out. I need to talk to somebody. My girlfriend just -- is pregnant. She showed me the pregnant test. I should propose, right? That's what you do in this situation, right? If you weren't pregnant, you wouldn't get married? Not right now, no. Maybe you should go to the doctor. You think? We're pregnant. Oh. This woman can't look away. Life-changing. Reporter: She's fully engaged in the drama. And as soon as jasmine leaves -- congratulations. Thanks. This is, like, so crazy. I don't know if I want to marry her. You've got a mess on your hands. I guess I'll kind of have to. You don't have to. Reporter: Will she tell him why. There's a woman that was pregnant. She brought her the test results. Reporter: Now, that's a real positive. How are you? I'm john quinones. Pretty amazing. Out of all of the people saw that go down, that was the only person who blew the whistle on the deceptive girlfriend. Most folks covered for her, including a man. And tonight, you're not going to believe how he responds. Said it wasn't their business. That's right. John, thanks very much. Provocative. Watch the season premier of "what would you do?" Tonight at 10:00 on abc. And coming up, forest
This transcript has been automatically generated and may not be 100% accurate.