"I think some people were embarrassed that they didn't realize what it was about in the beginning -- that they had been dancing to it."

Billboard is celebrating the 2010s with essays on the 100 songs that we feel most define the decade that was -- the songs that both shaped and reflected the music and culture of the period -- with help telling their stories from some of the artists, behind-the-scenes collaborators and industry insiders involved.

“Pumped Up Kicks” was the ultimate breakthrough for Los Angeles-based alt-pop group Foster the People. It was a catchy crossover hit that catered to multiple genre formats, and it helped usher in a new era of commercially successful indie-leaning pop music. Plus, it turned frontman Mark Foster from a L.A.-based jingle writer to a sought-after rock star.

So it may be surprising that, when reflecting on the song eight years after it reached No. 3 on the Billboard Hot 100, Foster says he might be ready to retire the song for good. “It’s something that I’ve been wrestling with,” he tells Billboard.

Why would you retire your most popular song? Well, it’s complicated.

Foster The People had only just begun when “Pumped Up Kicks” took off. Foster, who wrote, produced, engineered and plays each instrument on the recording, first created the drumbeat to sound akin to Fleetwood Mac’s “Dreams,” and then crafted the lyrics. The song details a troubled teenager with homicidal thoughts that many people later took to mean a school shooting -- written from the perspective of the teenager, the chorus is a warning to his victims (“You better run, better run, faster than my bullet”).

The song was tailor-made to be a hit because of its undeniably cheery melody -- something Foster excelled in as a jingle writer before starting the band -- and danceable groove. Plus, the title “Pumped Up Kicks” doesn’t necessarily suggest the seriousness of the song’s subject matter. This all led to some people being taken aback when they realized the dark subject matter it addressed.

“It took people a while to let the lyrics get into their bones and I think that once the lyrics got under their skin it was a bit of a slap in the face,” Foster says, “And I think some people were embarrassed that they didn't realize it in the beginning -- that they had been dancing to it.”

That juxtaposition is part of what helped the song take off and then, later, what also brought it back down to earth. On December 14, 2012, a few weeks after the song had peaked on the Hot 100, the Sandy Hook Elementary School shooting happened, and radio stations began to pull the song. MTV went as far as to remove the words “gun” and “bullet” from the chorus, and Columbia Records, which the band had signed with only months prior, began receiving complaints claiming the song was glorifying school shootings.

“I think people kind of filled in the blanks that it was about a school shooting, but I never say anything about a school in the song,” Foster says. “It's really more about this person's psyche. Obviously the song is speaking about violent things, but it is a misconception that it's about a school shooting.”

“Kicks” wasn’t the last of its type. Alt-pop had an unexpected moment in the sun during the early 2010s that culminated with fun.’s “We Are Young” and Gotye’s “Somebody That I Used To Know,” which both reached No. 1 on the Hot 100.

Not only was “Kicks” sonically influential, but it also aligned with many of the political issues that were beginning to plague our country. Hundreds of mass shootings have happened in the U.S. since Sandy Hook, and “Kicks,” albeit incidentally, helped create a conversation about it.

Foster The People is still making hits today. They’ve returned to the Hot 100 twice since “Pumped Up Kicks,” first with follow-up single “Don’t Stop (Color On The Walls)” in 2012 and, more recently, with “Sit Next To Me” last year. The latter single hit No. 3 on the Hot Rock Songs chart -- the group’s highest entry since “Kicks” hit No. 1 in 2011. Their success on the chart has also helped the group finish the 2010s at No. 19 on Billboard’s Top Rock Artists of the Decade ranking.

Foster adds that what made “Pumped Up Kicks” special was the fact that it resonated with people. “At some points I make music to bring awareness to something, but I make music to connect with people, and I feel like the awareness that song brought and the conversation that song brought, that’s been fulfilled.”

So nearly a decade later, Foster says it’s time to move on.

“Shootings have continued to happen and I feel like there are so many people that have been touched either personally or by proxy, by a mass shooting in this country, and that song has become almost a trigger of something painful they might have experienced,” Foster says. “And that's not why I make music.”