Sheldon and Amy do an on location special episode of Fun with Flags that includes Howard and Raj as the "house band." They even sing a theme song!

Bernadette, Penny, and Leonard watch from the other apartment, and Bernadette reveals that Amy's apartment has been ready for works, but she's been lying to Sheldon so that they could continue living together.

They guys are having lunch together, and Sheldon says he's worried Amy is keeping something from him. Leonard finally tells him that Amy's apartment has been ready for weeks.

Howard suggests Sheldon hold on to that information until he needs it. When Leonard disagrees, Howard tells Leonard that Penny has been secretly moving his collectibles into storage a little at the time.

The truth comes out for both couples, and Sheldon agrees that he might like to continue living with Amy permanently. 

However, he becomes concerned when he realizes that moving in with Amy at Penny's apartment means he would no longer have his old room. 

Meanwhile, Leonard tells Penny he understands that she wants to help make his room more her own, and says she can make changes.

Penny redecorates the room, and Leonard finds himself hiding things in the other apartment.