Songfacts®:

• This buoyant piano-driven stomper was released as the third single from Mania. The love song was debuted by Fall Out Boy at House of Blues in Chicago on September 16, 2017. The band then performed the track two days later for the first time on TV during the Jimmy Kimmel Live! show.
• Celestial imagery is used to illustrate the enormity of the lovestruck guy's devotion to his girl. Bassist and songwriter Pete Wentz explained it is, "that kind of love you feel for someone because of their glitches not in spite of them… where you feel the vacuum of them everywhere… and your heart just feels like TNT, quicksand, and oblivion all at once."
• The song's music video features bassist Pete Wentz playing a starring role as we see him being attacked by llamas with a shovel after being tied up in the back of a car. Jaden Smith, who previously starred in Fall Out Boy's promo for "Champion", is credited as a Llama Wrangling Specialist in the tongue-in-cheek end credits.
  
  The clip is strikingly similar to the visual for Kanye West's song "Flashing Lights." Wentz told Kerrang: "It was meant to be a shot-for-shot remake of the Kanye West video Flashing Lights, but with llamas. I went out to the desert with my buddy Dustin and we shot it one night, but the problem was we shot it to the length of Flashing Lights, and The Last of the Real Ones goes on for longer, so we had about a minute to fill! That's why those credits go on forever!"
• Pete Wentz revealed during a January 2018 live fan Q&A that it was his nine-year-old son Bronx who suggested the band released this as a single.
• When the pop-punk band came back from a more than three-year hiatus with their 2015 album, Save Rock And Roll, they wanted to reinvent themselves as a modern rock group by enlisting a number of producers and guest acts from different genres. On this tune, they worked with the Canadian producer Carlo Montagnese, aka Illangelo, who is known for his collaborations with The Weeknd. But expanding their circle of influence was easier said than done, Stump told Kerrang: "We'd been working with Illangelo, who'd played song ideas to us, but I’m pretty resistant to other people's song ideas. I want to write the songs! But while he was cycling through stuff he played this piano loop and it was like I was in a trance. But I had to leave to beat traffic. So I get in the car and I write the entire song in my head, just off that piano riff. By the time I got home, I had the whole thing. It's super-illegal and I shouldn't even admit to this, but I would be at stoplights looking at Pete's lyrics, figuring the song out. I was so inspired, man."
  
  Wentz added: "It was kind of serendipitous. We weren't looking for that song in that moment, but that's what came to us. Right place, right time."