You’ve sold more than 25 million albums of swelling, romantic ballads that make women weep. Your new album, Stages, is mostly Broadway songs from A Chorus Line, Les Misérables and other shows. For people who don’t know your music, how would you explain what you do?
My music has always been a little hard to define. It’s rooted in more classically inspired pop music. In the 1960s, 1950s and 1940s there was a much more full, rich, fluid style of singing, everything from Johnny Mathis to Mario Lanza. I generally shy away from saying it’s opera or classical, out of respect for that music. It’s a more traditional pop music that people aren’t used to today. Emotionally, a lot of the stuff I do is romantic. I tell the guys who come to my shows, “This is two hours of a very long night.” Wink wink, nudge nudge. I’m the amuse-bouche, if you will.

So can we look forward to the Josh Groban “You Will Get a Blow Job at the End of the Night” tour?
[Laughs] Listen, no guarantees, but it is highly probable you’ll get a BJ—or at the very least an HJ—by the end of the night.

Your success was a surprise even to most people at your record company, wasn’t it?
The label didn’t expect me to sell a lot of records, so I didn’t either. They said, “If you don’t have the support of radio, you’re screwed. And if you don’t have MTV, you’re fucked.” I took a leave of absence from Carnegie Mellon, thinking I’d make an album and then go back to school. I was blissfully naive about how awful the business can be, because I was 18—a young 18, not like, Tyler, the Creator 18. I was selling 800 copies a week. Then 20/20 aired a piece on me, and my album started selling 80,000 a week. I was shocked.

So you don’t need MTV if you have 20/20 and Oprah Winfrey?
Exactly. That was a huge deal when she said, “You guys have got to hear this person.” I was very sick the first time I went on Oprah; I had laryngitis and strep throat simultaneously, and a really bad pair of leather pants I bought at Ralph Lauren. They looked great on the mannequin. I basically had the outfit of a Nick Kroll character—I was Nash Rickey. Oprah had a show titled “Talented Kids,” so I thought I’d be following Johnny Wunderkind playing a Beethoven concerto, and then here’s Joshy Groban, the pimple-faced baritone. In show business they say don’t ever share the stage with kids or animals. But she’s had me on about 10 times. She can ask me any favor now. I’ve done a couple of Skype songs for Oprah. She’ll be sitting in her living room and I’ll get a Skype call, “Oh, it’s Lisa’s birthday.” “Hey, Lisa, what language do you want me to sing in?” I’d even squeeze back into those leather pants for Oprah if she asked.

What was the 14-year-old Josh Groban like?
The 14-year-old Josh Groban was not doing well in school, was kind of a sensitive kid, wore his heart on his sleeve and found the idea of going to second base to be outrageous. At summer camp there was a 14-year-old in our cabin who’d gone all the way—or said he had. We gathered around like he was a wise sage. “So, wait, do you have to ask before you touch the boob? How do you get your hand there?” I was a scrawny kid with Harry Potter glasses—I looked like Woody Allen and Howard Stern had a kid. There were a lot of fast-moving kids in Los Angeles who had rich-kid parties, and I came from a Norman Rockwell upbringing. If I inhaled secondhand smoke, I could see my parents sitting on my shoulders, going, “We’re very disappointed in you.” I was bullied. I had ADD, and I switched schools a few times because I lacked confidence. I was hopeless. But that’s how wit is invented.

Are you to blame for Il Divo, and are you willing to apologize?
[Laughs] I’m probably indirectly to blame for Il Divo. It was a perfect storm: I had a huge record, boy bands were still a thing, and Simon Cowell just, I don’t know, got drunk one night and decided to put Il Divo together. In any genre there will be marketing ploys and things manufactured to hit a formula, whether the audience is tweens or old ladies. I can’t hate all that much, because when I started, people probably thought I was a manufactured version of Andrea Bocelli and the Three Tenors.

You often do Q&A sessions during your concerts. What have been some of the highlights?
People get weird. I get so many marriage proposals. I should just build a compound, like Bill Paxton on Big Love—“Leave your families and come live with me, sister-wives.” I also get people who want to propose to their significant others, and half of me is hoping it goes great, while the other half thinks it would be fun to have an embarrassing proposal that goes viral, like those YouTube clips where a guy is hiding inside a shark costume and then the lady runs off.

Have any rappers approached you about collaborating?
At one point I was e-mailing back and forth with Lauryn Hill, but we lost touch. There was also a point—it was crazy; I couldn’t believe it—when Tricky called me and said, “You’ve got a fucking brilliant voice, mate. We’ve got to do something together. We’ll change the world with one song.” If there’s one genre that’s expanding in weird, wonderful ways right now, it’s hip-hop. Every rapper at the Grammys has a 30-piece string section behind them. All my classical friends are, like, painting their faces and playing with Kanye West now. I already sang Kanye’s tweets on Jimmy Kimmel’s show, so the least he can do is put me on a chorus.

If you could work with any rap group, who would it be? Wu-Tang Clan?
Yes! Josh Groban ain’t nothing to fuck with. That’s the truth.

Do you still have anxiety dreams about being onstage?
I still get really nervous. It kills me how much I fucking care. It doesn’t matter how small the show, I care so much that it’ll drive me insane. I downloaded this sleep-talking app—your iPhone has a built-in microphone that senses when you start to talk, so in the morning you can listen to all your ramblings. I become Shia LaBeouf in my dreams. “Oh my God, oh my God. No! No! No! No!” I’m freaking out in all my dreams. Oftentimes I wake up but don’t know I’m awake, and I think I’m somewhere I’m not—like in an alleyway. “Wait, I’m not supposed to be here right now.” I jump out of bed a lot.

What do you make of these disturbing dreams?
Well, doctor, I probably shouldn’t drink so close to bedtime. I shouldn’t eat dried mango and have a sugar high before I sleep. I don’t think it’s any secret that I’m a super-stressed person. I’m very high-strung and anxious, and I have to keep my shit together, so it comes out in my dreams: I’m running in slow-motion, with my pants off, and then I jump on a dolphin and escape. I scared a girlfriend only once. She said, “Do you know what you were doing in your sleep last night? You were slicing your arm on my torso, like it was a saw, and saying, ‘We have to cut it in two.’ ” [laughs]

Your girlfriend is Kat Dennings, the brunette from 2 Broke Girls. What did you do on your first date?
We met at a birthday party for Diva Zappa. It was a fix-up, which rarely works out. We had one of those moments when the rest of the world falls away, like, “Oh, cool, my person.” For our first real date we went out to dinner and were both nervous. We trolled some people on Omegle, a Chatroulette-style site but without video. You get thrust into a random chat, and we were messing with random people for an hour and sipping pear soda, just being total dorks. Sometimes the girl you dream of being with is just as much a nerd as you are.

Whom do you envy?
Miley Cyrus, because she has a pet pig, her Instagram account is on-point, and she gives no fucks. I think she’s happier than anybody else in the business right now. I have a hard time living in the now, relaxing and celebrating the moment. When I meet people who are living the dream and are okay with high-fiving themselves, I envy them. I’m always antsy about what’s next or hypercritical about what has passed.

Would you be willing to license your signature hit, “You Raise Me Up,” for a Viagra commercial?
Absolutely! Listen, that song has reached so many women in my career, it’s about time it helped some men. Anytime you have an unexpectedly explosive hit, you celebrate it, but you also feel shackled to it. There are times I’ll get sick of it, for sure. I can be cynical about it backstage—“Do I really have to sing it again?”—but as soon as I’m onstage and feel the reaction from people who want to hear it, the entertainer in me takes over.

What’s the interview question you’re most tired of being asked?
Probably “Where did you and Kat go on your first date?”

Touché. Your music is extremely romantic, but it doesn’t express all your personality, does it?
I sing serious music, and I hope it gets a serious reaction. But on the flip side of that, I love the silliest, dumbest humor. I was the class clown. When I started out in this business, there weren’t a lot of opportunities to show those sides of me. There was no Twitter, there was no one like Jimmy Kimmel giving me those chances. I’ve loved not being as precious in the past five or six years and taking the piss a little bit. In the beginning my management was afraid I would tarnish my image. I don’t think I’m a particularly inspiring guy when I’m not onstage—it’s just not in my DNA. Nor am I a huge romantic when I’m not singing. If I didn’t have music, I’d probably just be a quasi-funny, cynical, dark, introverted, nonromantic guy.

The music you sing takes great effort and thought and musical range. When you hear Top 40 songs on the radio, do you ever think, Who the fuck are these talentless assholes?
[Laughs] Yeah, a few times. “What is this shit?” But if I decided to write a song like that, could I? Maybe, maybe not. It’s a different universe, with its own struggles. If you’re a Top 40 artist, there’s the stress of constantly trying to stay on top. And there are some great singers on the radio: Adele, Lady Gaga, Sam Smith, Hozier, Ed Sheeran.

When you hang out with your pal Kid Rock, do you go to his house or does he come to yours?
I don’t live in Malibu anymore, so we haven’t hung out in a while. We probably couldn’t be more different as human beings, but we’ve had some very interesting nights together. I vaguely remember putting on, over my clothes, the cheerleading outfit of a stripper who’d been there the night before and then dancing on Kid Rock’s pole. I was very drunk. Mike D was there, and I played the organ, and then we smoked cigars. He also had a brilliant English professor there. I was thinking, This is nuts.

There’s no way Kid Rock hasn’t offered you drugs.
Never. Not once. You and I talked about people I envy—sometimes I envy great people who play the piano or guitar, because they don’t have to worry about their voices crapping out. They can have a terrible hangover and go onstage and tear it up. Maybe when I was 20 I could have gotten away with that, but not at 34. You have to sacrifice a lot of things in order to have the high of making 15,000 people go ape-shit when you sing. I’m a control freak. I’ve dabbled in a couple of things, but coffee is my drug.

You’ve “dabbled” in drugs? What does that mean?
I tried pot a long time ago and hated it. It made me paranoid. And it left me with a sore throat the next day, when I had to do a really serious song for a teacher. I’m not anti-pot, by the way. I think it causes fewer injuries than alcohol, but it wasn’t for me. I’m sensitive to chemicals. If the Advil bottle says to take two, one is enough for me. Remember those high school public-service announcements where, like, a girl goes to the bathroom to sniff a Magic Marker and then dies? That would be me.