Things go back and forth for Amy and Sheldon in "The Big Bang Theory" season 9. First second, one of them thinks that they should get back together and the other does not and the next thing, it's the other way around. This is what will happen in the next episode titled "The Earworm Reverberation."

In the previous installment, Amy told Sheldon that she is ready to give their relationship another try. Sheldon, however, said that they are better off as friends. This pushed his ex-girlfriend back to Sheldon-obsessed Dave as her attempt to move on.

In the upcoming "The Big Bang Theory" season 9 episode, Amy will give Dave a chance by going on a date with him. But it looks like it won't be a long night for the two. Thanks to Beach Boys, whom Sheldon has been listening to, Sheldon mustered the courage to get his girl back in his arms.

To win Amy back, he tells her that she is an "earworm in his heart," alluding to the Beach Boys song that apparently made him realize how important Amy really is and how he really wants him in his life as his partner.

And it looks like Sheldon's "earworm" line will work on Amy after all. As previously teased, the soon-to-be couple will end up sleeping together in an episode 11 of "The Big Bang Theory" season 9 airing on Dec. 17.

"After over five years of dating, we felt the time was right for Sheldon and Amy to finally consummate their relationship, and we're so excited for the audience to see the journey over the next several episodes," executive producer Steve Molaro told Variety.

Meanwhile, "The Big Bang Theory" season 9 episode 10 will also see Raj and Howard promote their band, only for their attempt to end badly. The episode airs Dec. 10 on CBS, after the show's short break.