Transcript for Sour Sixteen
Reporter: Sweet 16. It's practically a right of passage for teenage girls. And these days, the birthdays are bigger than ever. On mtv's reality show "my super sweet 16," exotic animals and fancy cars are the standard. And viewers love to hate the bratty behavior. Mom! What the hell! I don't want my car now. Everyone listen to me! Reporter: Our hidden cameras are at diane and company, in new jersey, and this birthday girl is about to go from super sweet to super sour. Hi, I'm mel knee and I'll be playing the sour 16-year-old. Reporter: "What would you do?" If you were face to face with this spoiled brat? Tweeti itreating her mother terribly. I'm embarrassed to be standing in this store in this dress. What are we supposed to do? Mom, shut up! Reporter: With our actors in place, we begin to roll. Our mom, michelle, pretends she's had a custom dress designed for mel knee. She's trying it on for the first time. I'm really hoping she likes the dress. She hasn't seen it. The sharks are back in an all-new season of "shark tank," where hopeful entrepreneurs from across the country dream of a chance to secure an investment and gain powerful partners to start, grow, or save their businesses. I'm asking for $100,000. Ba-bam! Stop the madness. If the sharks hear a great idea, they're ready to invest using their own money. Whoa! Oh! You're turning down almost a quarter-million dollars from mark cuban? Unbelievable. Now I've seen everything. And they'll fight each other for a piece of the action. The offer robert is making you is the kind of offer they made in medieval times when robber barons stole people's companies from them. But first, the entrepreneurs must convince a shark to invest the full amount they're asking for, or they'll walk away with nothing. It's one of the most interesting inventions america has ever seen. It sold out in ten days. Are you kidding me, mom? I'm not wearing this to my sweet 16. I look disgusting. Honey, this is the dress that we picked out. No, it's not, mom. Yes. This is disgusting. Reporter: Melanie's not only throwing a fit -- but I -- I think -- it will look great with these shoes -- no, mom, I'm not wearing this stupid shoe. I'm not wearing the dress. Reporter: She's throwing a shoe. And this mother of four has had it. You crossed the line. I think -- owe your mother respect, okay? 16 years old, apologize to your mother or I'm calling the manager. And you did your mother a huge disservice by speaking to her life that. Reporter: But wait, donna learner's daughter has a few words of her own. You don't even care that she's crying. You heard her saying how excited she was. You still haven't said sorry. Reporter: But melanie just won't back down. It isn't your business. Yes, it is. In 25 years, when you have your kids, that would be your shining moment. This is your mother's shining moment. My shining moment. My sweet 16. Reporter: Well, actually, it's my shining moment. It's "what would you do?" Oh, my god! Reporter: You stood up. I saw how she paraded out and I couldn't let it go. When I saw her throw the shoe, that was -- Reporter: That's it. We're rolling again, and this mother-daughter trio is about to take a completely different approach. This is cheap. Don't touch me. Look, you look beautiful. I'm going to look for something better because obviously you can't. Reporter: They don't dare take on melanie. But with the coast clear, they quickly console her mother. At that age, they want what they want. I picked out new dresses. Can you go look? They're a lot better than that. Okay. Excuse me, ladies. My mom is just such a loser. Reporter: Joanne tries to talk some sense into our badly behaved daughter. Your mom is trying to help. She wants the best for you. This is -- no, she doesn't. This is a pretty dress. Just jealous of me. Why would your mom be jealous? Have you seen her? Reporter: It's our last scene of the day and melanie is about to meet her match. You really blew it, once again. Stop it. Look. Here -- I got these shoes -- no, mom, I'm not trying the shoe on. The shoe's ugly, the dress is ugly. They don't even match. Do you see this dress? Reporter: These two women just won't hold back. Your mother didn't make , first of all. Yeah, really. Do you know how you're hurting her? You're hurting me. I hope when you're her age and you have a daughter who is 16 she never speaks to you the way you're speaking to her. Look at the trash she picked out. If you were my daughter, you would have no sweet 16. Believe me. Roll your eyes, do what you want to do, honey. Reporter: Just when the women think they've won the battle, melanie is back with one dramatic final blow. I'm going to fix this dress. No -- what are you doing? You are not cutting this -- now you're going to have to buy me a better dress. Oh, this is disgusting! Honey, you're terrible. Me? You should be ashamed of yourself. This dress is terrible. Nothing will make you look good with that attitude. That's a disgrace. That is a disgrace. Not pretty on the inside, how pretty can you be on the outside? Really. She didn't say anything to you. I would have threw you back in the damn dressing room and left. Are you insinuating I'm bratty? Yes. Bitchy would be more like it. Yeah. Excuse me? Yeah, you heard us. Excuse me. Th Reporter: That's enough to send melanie storming off. Slam the door. Reporter: And us storming in. Oh! Oh, you got to be kidding me! It was despicable that little girl. My husband used to say, the more you give them, the worse it is. Reporter: Your advice for mothers and daughters like that? Respect their parents. Reporter: And we've got one last lesson for this sour 16-year-old. Revenge is sweet.
This transcript has been automatically generated and may not be 100% accurate.