Penny and Amy are busy imitating the players of a video game. Amy says that she is good at it because she has a very low centre of gravity like a Pyramid. Leonard refuses to join them, saying that he cannot enter an ER with another video game injury. Sheldon also refuses to take-up the offer as he has to go to Texas. He is all set to become Uncle Dr Cooper. Sheldon's sister due date is near and Sheldon is expected to fill in for a husband who is recovering from a horrible motorcycle accident.

Sheldon has gone home and rest of the gang gather to decorate the Christmas tree and the room for a Christmas party. Stuart joins them. Sheldon calls-up and tells that it was thoughtful of them to celebrate Christmas in his absence. He complains about his sister wanting to give birth at home. The call ends when his mother calls him up to be in the family picture before the birth of the baby.

Bernadette suggests that they can watch "It's A Wonderful Life." Leonard imitates Sheldon's three knocks, which makes Amy to point out that things would not have been the same if Sheldon was not present in their lives.

Leonard and Penny would have not been dating. Howard would have not met Bernadette. Amy would have still been alone. Leonard objects he would have still met Penny as he has going to Cheesecake Factory for years. Penny imagines him peeing in his pants while failing to ask her out. Leonard says that she would have been with Zack. Penny's ex-husband would have come home, saying that he has got magic beans. Leonard imagines both Zack and Penny peeing.

At the Cheesecake Factory, Bernadette would have decided against approaching Howard after watching Raj over-the-top motherly kind bonding with Howard. Howards would still be staying with his mother. Howard imagines taking care of a dead mother. Leonard and Raj may have shared the apartment. As a result, Leonard would have bloated into a huge size because of Raj's pampering and cooking. Amy imagines being alone, singing happy birthday to herself and shedding tears. She also imagines Penny throwing herself at Sheldon in the laundry room and Sheldon telling Penny that he is only Amy's man.

Sheldon calls up and tells he has seen things, lady things. He describes the birth of the baby as some dirty magic show and it is like people coming out of people. Amy tells Sheldon to go be with the baby as he had often complained about the absence of a genius figure in his life while growing-up. Sheldon listens to her advice. Leonard points out that Amy is the one person who has made a difference in Sheldon's life.

Amy does not think so and talks about having a 50 pound sack of rice, with Sheldon's T-shirt on it. Leonard gives Amy an early Christmas present by showing her that Sheldon has made her a screen-saver on his laptop. Amy is happy to see that despite soon realising that she is part of an assorted mix. She thinks that she is the hottest one. When Sheldon returns, Amy tells him that she missed him and wants to know if he missed her. Sheldon replies that he almost preffered to have her there, or instead of him.

Stuart is all alone at the Cheesecake Factory, eating a pastry. He imagines that he is the cool dude dating Penny. A bloated Leonard asks Penny for her phone number and Penny tells him that she has a boyfriend. Stuart imagines Penny kissing him and walking out with him.