Robin Thicke is back to perform "Complicated," a song that really stays in Oprah's head. "I get up in the middle of the night and I'm hearing it in my head," she says.

Watch Robin Thicke sing "Complicated." 

Robin says the song is about him. So what makes him complicated? "You know when you're in a relationship and you keep focusing on the negative things? Maybe the past or the problems and you can't push forward, you can't make anew?" Robin says. "So I was going through that with my lady where I kept focusing on the past and the negative things."

"But writing that song, I'm sure, helped you straighten things out," Oprah says.

"Yeah. In fact, she was the first one to hear it," Robin says.

For more information about Robin, visit RobinThicke.com.