With little else to do on a mid-pandemic January night, the future members of Wet Leg decided to have some fun improvising on a drum machine and synthesizer at home on England's Isle of Wight.

Among the lyrics they conjured on the spot were lines from "Mean Girls" and a nod to a piece of furniture one of them was seated on.

That ad-libbed tune, "Chaise Longue," has propelled the friends across the Atlantic, from the English Channel to sold-out music venues across America, including First Avenue on Thursday — a show that got bumped up from St. Paul's Amsterdam Bar due to high demand.

"It's all been so surreal," Wet Leg guitarist and co-vocalist Hester Chambers said by phone from London last week ahead of their U.S. tour kickoff in Milwaukee on Wednesday.

Chief bandmate and best friend to lead singer Rhian Teasdale, Chambers credited their unexpected success primarily to that one silly but infectious song, sort of a cross between the B-52s and the Strokes with its choppy groove and playful, atonal vocals.

"We hadn't even formally started a band yet when we made it up," Chambers said, launching into the story of how "Chaise Longue" came about little more than a year ago.

"It was just a regular evening in January where Rhian was sleeping over at my house. Joshua [Omead Mobaraki], who plays guitar, lives with me and made this beat on a drum machine. The bass line was originally done on a synth, and we just started freestyling the lyrics over the groove."

"The next morning, we listened back, we thought, 'Oh my gosh, that's a weird song that will never see the light of day.' But then we kind of grew a bit attached to it."

So did the U.K. tastemakers at Domino Recordings (Arctic Monkeys, Franz Ferdinand), which signed up the band and issued "Chaise Longue" as a single last June. The song quickly became a viral hit, then a radio hit, including a Twin Cities spot atop 89.3 the Current's "Chart Show."

After just a few well-received festival and club appearances, Wet Leg has become one of the top bands to watch in 2021. As you might glean from the tone of their big hit song, they aren't taking the hype — or themselves — too seriously.

"We named the band Wet Leg, so how serious could we be?" Chambers cracked.

"We feel very privileged to be making music with our friends pretty much full time now, so it feels important to us now. But it's important to have fun, too."

So far, Wet Leg has released only three other songs, including the wryly suggestive "Wet Dream" and the punkier blaster "Oh No." Each will be featured on their eponymous full-length record, due April 8.

Here's more of what Chambers had to say about the album and the buzz around what she openly admitted "is still very much a baby band."

On touring before their debut LP is released: "Initially, we were a bit nervous, but people at the shows would say afterward, 'Oh, what was that one song you played?' They were excited about the other songs, and we got excited because of it. I think it can be enjoyable as a different kind of experience, as opposed to going to see a band where you know all the songs."

On what to expect from the rest of the record: "There are some deeper feelings on it, some thoughtful innuendo, a little of this, a little of that. It's hard to describe it. But I will say that among the songs that we've already released into the world, there are songs on it that are quite different."

On their follow-up single "Wet Dream," which has tested radio standards with its innuendo-laden lyrics: "It's really not all that dirty in our minds. We were quite surprised when it was suggested we do a radio edit for it and change some of the words, when you have a song like 'W.A.P.' become such a big song. I think it highlighted a difference between indie music and other genres in terms of what's accepted."

On the Isle of Wight and how it defines the band: "Honestly, I don't think it influences our music that much, but it does play into our visuals — almost out of necessity. We made our videos [for 'Chaise Longue' and 'Oh No'] in lockdown when we couldn't really go anywhere else. We're happy we got to show it off, because it is a nice place. But we didn't have much of a choice."

On whether their success demonstrates a COVID-era demand for fun, lighthearted rock music: "I think that's fair. Everyone has gone through such a kind of manic time, it's been scary, I think people are looking for any kind of a coping mechanism. But that said, we also have some sadder songs. As much as we want to only have a good time, that's kind of impossible to do." She laughed.

Wet Leg
With: Lowertown.
When: 8 p.m. Thu.
Where: First Avenue, Mpls.
Tickets: Sold out.
Online: wetlegband.com