This cut was influenced by vocalist Justin Pierre's experience of being with his grandmother a few hours before she passed away. He explained to Spin magazine: "My grandmother died late in 2009 and it was the strangest thing. I was trying to go back to film school when we had this big break, this big opportunity. But I wanted to see her because I knew she had cancer and was on her way out. Something told me I just had to go see her. I had to put my life and band on hold and say, 'Screw it!' and go hang out with her. I flew down to L.A. the next day and hung out with her.
It was a weird experience being with this shell of a woman that I used to know," he continued. "She couldn't move or communicate. I didn't know what to do. I hung out with her for a few hours and she died the next morning. If I hadn't gone, I would have never experienced that. And that experience might have been what set me towards this idea of just existing and living in the moment, and that definitely plays into the record. 'Happy Anniversary,' this sad new song, is based on that experience. It's from the point of view of the someone who is dying. It's one of the songs that I'm very excited about."