This song finds Kesha lamenting over a lost love. The singer penned the tune with American musician Ammo, who is signed to Dr. Luke's publishing company Prescription Songs as a producer and songwriter. Ammo has also written and produced songs for Pitbull and Jordin Sparks.
Kesha told Spin magazine the song is about a former lover of hers. She explained: "'Harold' is about the only guy I've ever been in love with - and our relationship didn't work out, obviously. When I went to write it, I locked myself in a room and cried like a little bitch. I can't even listen to it. But I wanted to do a vulnerable song because it's a side of myself that people haven't seen."
Kesha refused to hide her old flame's identity with a pseudonym. The singer explained why she used Harold's actual name to Spin Magazine: "He's not getting away with a fake name. All men that date me have to know that their name may end up in a pop song. It's the best revenge: you can't get arrested for it, and everyone knows about it. And I like to be specific — I don't want any of the other losers I've dated to think the song was about them."
Kesha explained to Rolling Stone that she really did sneak into a Rolling Stones concert with Harold, which is something she got pretty good at. Said the singer: "Harold was my first boyfriend, and one of our first dates was sneaking in to see The Stones at Hollywood Bowl. I never even paid for a movie until recently. I snuck into a Strokes show and lost a shoe, but I got in there. I snuck into Coachella four years running. One year I ended up onstage with Björk. I always wear flat boots so I can climb."
Movie director Michel Gondry played live drums on the Late Registration track, "Diamonds From Sierra Leone." The Eternal Sunshine of The Spotless Mind filmmaker happened to be in the studio on a day when producer Jon Brion was setting up a drum kit