Transcript for How YouTube's 'Hot Ones' 'humanizes' celebrities with hot sauce-covered chicken wings
Reporter: The lights, the cameras. It's different hot. Reporter: The questions. Is it difficult just sitting there knowing that any gesture, any facial expression could become a viral news story? Reporter: Chrissy Teigen is clearly on an interview show, but why is she sweating? She's just one of the countless a-list celebrities appearing on the interview show, "Hot ones." From Gordon Ramsey to Scarlett Johansson and Shaq. This one got me. God! Reporter: It's the online show known for putting guests to the test with hot wings and even hotter questions. My voice is changing. Reporter: With millions of subscribers. Hot ones is keeping the craft hot sauce market sizzling. Why hot sauce? For us, it's like celebrity is so unattainable by definition. What's more common, man, than dying on hot sauce? Reporter: Host Sean Evans invited us to the set to talk about all things spicy. We didn't really know we had lightning in a bottle necessarily. You see people who are on red carpets, in front of flashing bulbs, then here they are sweating their faces off, spitting in buckets and trying to survive this show. Reporter: With a little heat pushing the stars to the limits, it's not your average interview show. What is the best reaction you've ever gotten? Physically, the reactions have been great. Russell brand did an impromptu song. Bread baker I can look at each one of these episodes and find something a little special about each of them. Reporter: With each wing the sauces get a little hotter, questions a little tougher and the answers a little wilder. He hot. So hot. Reporter: What is it about the hot sauce? You're breaking news all the time. There's that great Mike Tyson quote, everyone has a plan until you get punched in the mouth. And that's what the chicken wings do. They end up spillin' it. Reporter: Today it's my turn for punishment. Start at the handle, this is the classic. Reporter: First one up, hot ones classic. Cheers. Reporter: I can handle that one. This is hippy dippy green out of Vermont. Number three is the hot pepper garlic. Patio's potion. Reporter: You're waiting for me to cry. I can feel some sweat coming out of my brow. Same with me. My mouth is tingly. My lips are on fire a little bit. Reporter: Nine seasons in and Sean isn't just the host of the show. He's turning into the face of an industry. Reporter: Is hot sauce just in right now? You'll see, I think, an explosion in the craft hot sauce market. Increasingly I'll see commercials and every fast food chain has the spicy fries or spicy this or spicy that. I think hot ones is in the center of that storm in a lot of ways. Reporter: So we went with Sean to the Mecca for hot heads like himself. The nyc hot sauce expo. The world of hot sauce has ballooned to an almost $1.4 billion industry. And here Sean is like royalty. So are you used to taking selfies with fans? I never feel more famous than at the hot sauce expo. Cheers. Ah. Cheers. Cheers. Woo! Reporter: Sean is a lightweight. Steve Seabury is the man behind the event. One of my favorite is the reaper eating contest. You have 60 seconds to eat as many reapers possible. It's about enjoying the taste. These guys are making artisanal brands, ingredient-driven hot sauces. Reporter: Each is hoping theirs is a ticket to success. One has created an empire. Welcome to the magical warehouse. Reporter: They started making the sauce in 1980. Did you ever think it was going to get this big? No. Reporter: Now they ship across the U.S. And 27 countries. Is there a secret ingredient to the sriracha we don't know about? Pressed chili. Reporter: I can make it at home? Yes. You can make your own better than mine. Reporter: I doubt that. His humility shouldn't be mistaken for anything other than he cranks out some of the world's most sought-after sauce. Back on the set. We are halfway through with Sean Evans. We pull something from Instagram and have you explain the bigger Here I'm with joji in a Japanese convenience store. You know what's on our faces? That's a placenta face mask. Reporter: Your skin is perfect. Placenta face mask. Reporter: Let's try number seven. Torchbearer, the garlic reaper sauce. Reporter: Never had a killer reaper. You don't want one. This one's freakin' hot, man. Oh, buddy, we're here. I'm going to take off my jacket real quick. Woo! I'm hot, Sean. Keep going. Keep going. This is the one I am most scared of. I saw Shaq freak out after this one. Oh! Oh! Reporter: Yeah. All right. This is the experience. Oh, my god. Number nine woo! Can I have some more milk? This is pain. Real tears on my face. All right. Wing number nine. Let's go. Ooh. I'm honestly numb to a point. Yeah. Reporter: Everything hurts. I'm going to ask you about one more Instagram. I think that's Chrissy Teigen. It is Chrissy Teigen licking my face. I do remember. She was like, you taste good. Reporter: We have one more hot sauce to go. Ooh. Reporter: And for this one, it's tradition around here. Put a little extra on the last wing. Cheers. Reporter: All right, bottoms up. That's dip poison. And there it is, the cherry on top. How are you feelin' right now, though? Reporter: My face is on fire. I'm sweating like crazy, definitely feel like I'm tripping. Now we're here at the end of the gauntlet, as you chug down that milk nobody will take that away from you. Reporter: For "Nightline," Austin sing, and I'm on fire.
This transcript has been automatically generated and may not be 100% accurate.