KINGS OF LEON has opened for bands like U2, Pearl Jam and Radiohead and played before more than 150,000 British hipsters at the Glastonbury Festival. But for lead singer Caleb Followill, headlining Madison Square Garden is so big it’s vomit-inducing.

“I threw up all day yesterday,” says the 27-year-old Tennessean who, in support of the band’s fourth album “Only By the Night,” takes the stage Thursday at MSG with brothers Nathan and Jared and cousin Matthew. “It doesn’t matter where you grow up in America, you know what the Garden means.”

Being on the road with family must be tough. Who gets on your nerves the most?

I’m probably the one who gets on most people’s nerves the most, just because my drinking fluctuates.

Is that when your alter ego, “Rooster,” comes out?

Yeah. He’s the biggest nuisance. But he’s been gone for a while, hibernating. If I could’ve seen myself now back [when I was a kid], I would’ve been very ashamed.

You and your brothers are the sons of a preacher man named Leon. How big a role does religion play in your life?

I’m not living the life that I used to live. We don’t really go to church anymore. But I’m very blessed. I definitely thank God on a daily basis. [My father] is very proud of us. Our whole family is. We took this family name and did something with it that no one ever imagined.

And now you’re getting Grammy nominations and headlining the Garden.

Yeah. I’m still scratching my head about [the Grammys]. I can’t believe it. It’s a huge honor. And last night I was just flipping through the channels and there was a basketball game on at the Garden, and I got all shaky. Hopefully it’ll go over well and I don’t fall off the stage.

You should be OK. Do you have any pre-gig rituals?

We have this chant we do before every show. It’s hard to explain – it’s like a yodel. We all get in a circle and we hug it out. Then we sing a gospel song, say a prayer and wait for our tour manager to come in and give us a motivational speech. [Laughs.]

Seriously?

Yeah [laughs]. We put the pressure on the tour manager. We’ve gone through a lot of them.