"May 16" is a song by the US melodic punk rockers Lagwagon, off their album "Let's Talk About Feelings".
Why May 16? This's the significance of the song. Joey Cape:
You know, it was me, hungover in an apartment with some girl I went home with from the bar the night before. There was an acoustic guitar in the corner. I heard this ruckus happening in a park adjacent to the apartment complex, and it was just a wedding happening on this Saturday, May 16. And my heart just broke; this wedding that I hadn’t been invited to for someone I was so close to for so many years of my life, where a misunderstanding caused a falling out between us from some time before. That story is very long and I don’t want to revisit it, but I kind of picked up the guitar and the first thing that came to mind was: “It’s just another Saturday,” but obviously I was in denial. The melody and the song came together; by the time my new friend got out of the shower or whatever, I had this terribly sad song.