The theatrical new york pop-rock crew fun. has scored one of 2012’s hugest smashes with the crazy-catchy single “We Are Young” – lodged at the top of the charts for six weeks and counting. For singer Nate Ruess , who formed fun. in 2008 after spending most of his twenties fronting Arizona alt-rock act the Format, the band’s current run of sold-out shows has been a long time coming. “It’s pretty insane,” says Ruess, 30, checking in before a gig in Omaha, Nebraska. “I knew how touring was for 10 years, but it’s completely different now that things are popping off. I don’t play an instrument – I just write in my head, and I usually hear fully formed songs. ’We Are Young’ turned out so much like it was in my head. But it also exceeded all my expectations.”

Your uncle, John Ruess, acted in musicals. What’s he like?
He’s a real dreamboat. We’d see him tour through Phoenix, doing The Music of Andrew Lloyd Webber or Show Boat . When he did Les Misérables in Chicago, when I was 10, I fell asleep – my attention span was really shitty back then.

Did he teach you about life on the road?
I always saw him pounding water, so that’s a ritual of mine. I have this weird thing where I wake up three times a night to go to the bathroom, and I have to count backward from 20 before I finish peeing. Then I go to the sink and count backward from 20 and drink for 20 seconds out of the faucet.

So, you’re totally OCD.
People always have to sit on my right-hand side. But, no, I’m just as weird as anybody else. Everybody’s fucking weird.

Do you drink much before shows?
I’ve turned it into a schedule. I drink one or two shots of whiskey 30 minutes before we go onstage. Then there’s a nice break in the set where we play acoustic and I have another shot. After the show, I should stop, but I’m all jacked up, so I usually have one more glass of whiskey. Then I turn into what everybody refers to as Dr. Midnight. Dr. Midnight has no dietary restrictions. All fucking hell breaks loose.

The song “Some Nights” talks about sleeplessness. Are you more creative late at night?
For this album, yeah. I wasn’t finding much inspiration during the day, but when I’d wake up to pee, I’d have ideas. My girlfriend would be sleeping, so I’d turn the faucet on loud and sing into my phone. The next morning, it would sound like some freaky lullaby. That was where a lot of the writing started for the album.

You have a girlfriend? I thought your song “It Gets Better” was about growing up as a gay kid.
No, I’m not gay. You’re a terrible Sherlock Holmes. That song is just about losing your virginity.

How did you write “We Are Young”?
The lyrics came after my worst drinking night of all time. Have you ever been kicked out of a cab for puking all over the place? I have. The cabbie was demanding all this money, and all I could do was stand on the corner with my head against the wall. It took me another day before I was a functioning adult and could actually write down the verses.

Kanye West ‘s pal Jeff Bhasker produced the new album. How did you make that happen? He’d blown me off twice, so I didn’t think it was going to happen. When we finally met, I was pretty inebriated. I was like, “Fuck it, I’m going to sing him this chorus.” So I sang “We Are Young” – this thing that had been in my head for a week – and he straight-up freaked out. The next day, we got into the studio.

I hear you’re a huge Wilco fan. What do they mean to you?
When their documentary, I Am Trying to Break Your Heart , came out, I was about 20. I’d just made a major-label album and no one was responding to it. I was so depressed. That movie taught me you can make music you want to make, and people will come around. We self-released the next Format album in 2006, and it ended up selling 85,000 copies.

One of your old bands was called Nevergonnascore. How long did it actually take you to get laid?
[ Laughs ] I think I was 15. But don’t mix that up with being cool.

This story is from the May 10th, 2012 issue of Rolling Stone.