Christmas helped deliver an especially upbeat ‘Big Bang Theory’ that left all its characters smiling, though it didn’t start off that way.

It all began with Leonard and Howard conducting an experiment in the university’s clean room, one that goes well until a pigeon flies in, risking contaminating all of the equipment. Their struggle to get the bird out puts them at risk for missing the traditional Victorian Christmas dinner that Amy is throwing due to Raj’s parents divorce. When a Slim Jim and a distraction fail to lure the bird out the door, they call Raj in for reinforcements.

This leaves Penny and Amy to entertaining Raj’s father, who is harboring a ton of resentment over his recent divorce. Without the entire gang there to ease the tension Penny is forced to comfort the divorcee on her own until Amy suggests they play some traditional parlor games. The game in question? Blowing a ball of wool from one side of the table to the other.

The most entertaining dynamic is one that we rarely see. Bernadette offers to drive Sheldon to the party and spends the entire ride delightedly shrieking Christmas carols, much to his dismay. It’s this enthusiastic cheer that makes him resent Amy’s insistence they celebrate the holiday that leads him to his master plan. As punishment for forcing him to celebrate the holiday, he’s going to ruin Amy’s Christmas.

Sheldon being Sheldon, he chooses to do this by buying his girlfriend a present. When Bernadette questions his logic, he explains that since they had decided not to get each other gifts, he will give her the most thoughtful and genuine gift he can think of to make her feel guilty for not buying him anything. They spend the afternoon shopping after which even the mall Santa agrees that just dating Sheldon is “punishment enough”.

After Amy chokes on a ball of wool, Penny reaches her breaking point and calls Leonard, asking why he hasn’t arrive. By this point the guys have accidently killed the pigeon with a fire extinguisher, brought it back to life via CPR and been preparing to set it free, only to have another bird fly in through the open doors. Leonard explains they can’t leave because they can’t risk getting in trouble for accidentally contaminating the clean room. Penny reminds them its Christmas Eve, no one is around, all they have to do is erase their names from the sign in sheet and leave. They object, but in the episodes funniest moment, they cut to a clip of the guys gleefully singing carols in the car, clearly having taken Penny’s advice.

Penny’s plan was foolproof, but it was Sheldon’s that didn’t go accordingly. Amy is elated to recieve a photograph of her boyfriend sitting on Santa’s lap, in a frame that sings no less! Before he can revel in the glory of having gotten one over on her, she confesses she got him a gift as well. Amy baked Sheldon a box of cookies using his Meemaw’s recipe. Upon taking a bite he exclaims “They’re perfect. They taste just like her hugs.”

The couple are often played for laughs, leaving the more serious scenes to Penny and Leonard or even Howard and Bernadette, but its clear these two really do love each other and there’s no better time to show it than at Christmas.