Plot

Sheldon has a revelation when he realizes why a song was stuck in his head. Meanwhile, Amy invites Dave over for dinner despite their previously awkward date, and Howard and Raj become obsessed with a fan of their band.

Sheldon doesn't realize that he's humming until Leonard points it out to him. After that, Sheldon, and by association everyone around him, "descend into madness" in Sheldon's words as Sheldon tries to figure out the song which he is continually humming. As he racks his brain, he may or may not realize that the song has some special meaning in his life. Being rejected by Sheldon in her attempt to get back together with him, Amy decides to try another date with Dave despite the disaster that was their last date. He promises to keep Sheldon out of their date this time, which may be easier said than done. And Raj has created a fan page for his and Howard's band, Footprints on the Moon, which has received their first fan, Trent Monaco. Finding out what they can about Trent, they seem more enamored of him than he may be of their band.—Huggo

In the middle of the night (0225 hours) Sheldon is documenting his descent into madness on his phone. He needs to urinate, but it is still hours till his scheduled morning urination. He feels he is losing his grasp on reality and may soon forget what a toilet is.

Two days earlier Sheldon and Leonard are in Apartment 4A working on a physics problem. Sheldon is humming to himself though at first he doesn't realize he was humming. After Sheldon knows that he is humming he tries to figure it out and fix words to it. Leonard wants to work telling Sheldon just has an ear-worm that will disappear.

Later, Sheldon is on the phone trying to get someone to help him with the tune and is surprised the Rock and Roll Hall of Fame couldn't help him. Sheldon has an Eidetic memory and should remember it. He thinks that there is something wrong with him. Now Sheldon fears that he is starting his descent into madness where he tests the limits of public nudity. That means going barefoot outdoors.

Amy nervously calls David Gibbs asking if he wanted to try going on another date. He is happy to do so.

Raj is slumming in Howard's lab while Howard is busy working talking about the Department of Outer Space Affairs at the United Nations. Raj had set up a Facebook page for their band, "Footprints on the Moon". One person comments on their page telling them that their band rocks which excites them.

Sheldon is sitting at his piano playing the tune over and over again. Sheldon's other project is to leave his future crazy self-messages. Music is bad. Penny is his friend and he can accept any food that she gives him, especially since he probably paid for it already.

Bernadette visits Amy discussing her next date with Dave. She tells her that Sheldon turned her down. And that Dave was talking all night about Sheldon. Amy is making him dinner which Bernadette says is a big step since it could lead to sex. Maybe that's what Amy needs. Bernadette reacts that making her first time with a guy six-foot-seven is like taking her driving test with a bus.

Raj and Howard want to respond to their fans. Raj suggests: We may be "Footprints on the Moon'', but you sent us over the moon. Howard wants: Thanks for digging' our vibe. We'll keep rocking while you keep rolling. They posted it. Their fan's name is Trent Monaco. He's a DJ, brews his own beer, has tattoos and a hot girlfriend.

Penny and Leonard are trying to sleep as Sheldon pays the tune over and over again on his piano. Penny goes into Sheldon's room to his annoyance and then steals the piano from him. Problem solved. Then he starts playing it on his new tuba.

In the morning, Sheldon is again making videos for his future crazy self. The ideal thermostat setting is 72 degrees. Then he shows him his spot that he is very protective of. Anyone who sits there shows be berated, but in an adorable manner.

Raj and Howard are checking Trent out on the Internet. Bernadette reminds them that they only played together once. And at a children's hospital until they were asked to leave. Raj finds out that he is at a coffee shop and both of them want to meet him.

Their date starts well as Dave enjoys her meal since he usually doesn't get many home-cooked meals. His former wife wasn't much of a cook until she started cheating on him with the chef. Dave wonders how long she'd live there. About five years though she was thinking of moving to a better place now that she didn't have to be close to... She stopped and apologized for bringing him up. Dave was pretty excited to find Sheldon lived nearby. Dave changes the subject and asks where she got her neat model train from.

Sheldon continues to play the tune including gargling it. Sheldon then lists some scientific geniuses that were crazy. He follows with other notable people like Van Gogh, Pollock, Bobby Fischer, Brian Wilson of The Beach Boys...Something clicks in Sheldon's brain and he realizes the song is "Darlin'" by The Beach Boys. He is greatly relieved that he is not crazy.

Raj and Howard are at the coffee shop observing Trent who is listening to music on his laptop. Raj wants to go up to him, but Howard thinks it would be cooler if he discovered them. The guy's euphoria dies when they see Trent picking his nose and that didn't bother them. But eating it, that is too much to bear. While they make a hasty retreat, Trent does recognize them, but they deny it.

Sheldon is listening to the song and wonders why he was stuck on that one. Sheldon does realize why it was that song. It was about Amy and how she made his life better. Checking out the lyrics he finds the following: "I was living like half a man, then I couldn't love, but now I can, You pick me up when I'm feeling sad, More soul then I ever had." Sheldon calls Amy the dryer sheets of his heart and then goes to see her.

Amy and Dave are awkwardly sitting on the couch. Amy leans over to admire Dave's tie pin. He leans in and kisses her. Amy jumps back. As they approach each other, Sheldon knocks on the door. Dave is excited as Amy goes to answer the door. She tells Sheldon that it's not a good time. Sheldon says he doesn't care and that he had a song stuck in his head that he couldn't get out. The song was about her and he can't get her out of his head. Amy is like that ear-worm, but is in his heart. She is his heart-worm, but not the poodle killing kind. Amy doesn't understand. Dave jumps in saying, "If I may, I believe what he is saying in a charming and delightful way is that he loves you and wants you back." Amy is stunned as Sheldon realizes that she is on a date. Amy wants him to continue. Sheldon tells Amy he wants to be her boyfriend again and that he loves her. Amy tells him she loves him too. Dave pokes his head around the door again and cries "KISS HER, YOU BRILLIANT FOOL!" Sheldon and Amy then embrace and begin to kiss.

Finally, as Sheldon and Amy have not stopped kissing, Dave walks out telling them goodnight. Amy kicks the door closed as they continue.

Title reference: The effects of the song stuck in Sheldon's head which is called an ear-worm.