Sunday night is when I like to watch TV," says John Oliver, taking a rare break from planning his HBO fake-news show, Last Week Tonight, which airs Sundays at 11 pm. "Now I've kind of ruined that for myself." Having shed his on-air suit for a plaid shirt and gray jeans, the 37-year-old former Daily Show correspondent looks not unlike a hip, grown-up version of Bart Simpson's nerdy pal Milhouse, albeit with an English accent. (It's a "Brummie" accent, via working-class Birmingham, but he's amused that Americans find it impressively posh.) A Cambridge grad who spent most of his time there working on comedy skits, Oliver joined The Daily Show with Jon Stewart in 2006, bringing an expat's bemused perspective to the show's satire. He had never even visited the U.S. before then, but he's well settled now: His wife, Kate, is a U.S. Army vet he met at the 2008 Republican National Convention. (She hid him and his crew from security guards after he ventured into an unauthorized area.) As a correspondent, Oliver took on a vaguely stern persona, but the new show is a chance to present his real personality, which emerged when he guest-hosted for Jon Stewart last year – and found himself smiling on-air for the first time. "I was never like Colbert, a fully developed character," he says. "I don't have the performing skills to control it."

You once said that America is in its fat-Elvis years. Do you really believe that?
Yeah, definitely. But that's really mainly a compliment. To be fat Elvis, you've at one point had to have been Elvis. So, Elvis is one of the greatest singers who ever lived: icon, beautiful man, incredibly talented, rebellious, sensational person. Then, yes, he became a little dysfunctional later in life. But even fat Elvis was a pretty good Elvis. Sure, it wasn't black-leather-suit Elvis – it was busting-at-the-seams, white-jumpsuit Elvis. But America shouldn't forget, it's still fucking Elvis. You're still selling seats.

For a Daily Show sketch, you famously stood in the crowd at Obama's inauguration and literally told everyone they'd be disappointed.
I could feel the people around me going, "What the fuck is wrong with you?" I was right, though! But there's a difference between being right and alerting people to the rightness in that particular moment. Just let us have 30 seconds with our new president before injecting cynicism into it.

It's the Big Lebowski line: "You're not wrong, you're just an asshole."
I don't know if there's a better job description for a comedian than that.

For all the daily grind at The Daily Show, it must have been weird to have that train stop last December.
It was really, really weird. It didn't stop for that long, because I started work here on January 2, but for the first 24 to 48 hours, it was really different. I'm an emotionally repressed human being – I'm a comedian and I'm British, so that basically means there's nothing really happening inside [laughs]. But my last day at The Daily Show was immensely emotionally difficult. I cried on camera. It was pretty weird. Jon leans in and says, "Are you all right?" And that just finished me off. It was the complete embodiment of how all he's ever done has been incredibly caring. Then I could tell, to the minute – it's on 24 hours later in England – when it aired there, because I started getting this string of abusive texts on my phone going, "Oh, you are not fucking crying on TV, are you? Kill yourself."

How did the new show come about?
After Jon came back, I started wondering, "What should I do now?" Then HBO said, "What about doing a show on Sunday nights?" And I couldn't possibly say no. It went down so quickly that I didn't get to tell my wife about it. She was a combat medic in Iraq, but she now works with a veterans group that occasionally deploys to disaster zones. So she was doing triage after the hurricane in the Philippines, and I wasn't able to get in contact with her. And this decision was coming to a head. I spoke to her once on a satellite phone, but there is just no way to pivot that conversation. She's going, "Bodies, bodies, we're doing emergency C-sections." There's no way to say, "Uh-huh, uh-huh. I've got some news ..." So I had to wait and tell her when she got back.

Does that induce guilt, when she's off doing something like that while you're doing comedy?
It gives you the appropriate amount of guilt, which is a huge amount of guilt. A huge amount! If it induces anything other than a crippling amount of guilt, you are a platinum douche. So one of us has a life with some inherent, tangible value to other human beings, and the other one has one with zero value.

You love soccer. Have you become a fan of American sports?
I like the Mets. Miserable. I can't wait for another season of misery to be unleashed. I also picked the Jets. Smart move. I like dysfunctional underdogs.

Are you into outdoor adventures?
Outdoor adventures? I'm a comedy writer! I don't like to be outside in a city, let alone where there are things scrabbling around. I don't hike. I couldn't live off the land. My wife likes that show Naked and Afraid, where you're given nothing, maybe a knife, and have to survive naked in the wilderness for 21 days. We were watching it last night, and I was trying to work out when on Day One I would quit. I think it would be, like, the first sense of pulling my boxer shorts down my waist. I don't even think it would be, like, penis exposure; it would be tugging the elastic band and saying, "No, no. This seems horrible."

Who made you laugh as a young person?
As a really young person, adults falling over. There's just nothing funnier than seeing an adult fall over. It was my favorite thing. If they were carrying something, even better. To be honest, that still stands – I still like people falling over. Jackass is still very funny to me. YouTube clips of people slamming their testicles as they fall off a skateboard is still probably as hard as I'm going to laugh.

What made you realize you wanted to do comedy?
I must have been 18 or 19, and I did this two-man show that I co-wrote. It was probably terrible. But I remember coming offstage and thinking, "Oh shit." It was the kind of "Oh shit" that I imagine heroin addicts who take heroin for the first time have, where they go, "Oh, man. It's probably not great that I enjoyed that as much as I did. I think I'm willing to destroy everything in my life to do this more." Then I didn't do much schoolwork. I just wrote comedy for the three years I was there. You just hope you can be a high-end heroin user and not a guy slumped behind a bus station. But believe me: There is a guy slumped behind a bus station in me.