|6.9||Rated 6.9/10 (1050 votes)|
After Sheldon’s mother and Leonard's father share an evening together, everyone deals with an awkward morning the next day. Also, Penny’s family arrives for the wedding ceremony, including her anxiety-ridden mother, Susan, and her drug dealing brother, Randall.
Colonel Williams, an Air Force representative from the Department of Material Command sits down to talk with Wolowitz.
Tensions rise when the boys struggle to complete their government project on time and Sheldon tries an energy drink to stay awake. Also, Penny and Amy go to a “party” at Bert the geologist’s house, and Koothrappali learns Bernadette’s true feelings about her pregnancy when they clean out the future baby room.
When Amy’s apartment floods, she proposes a “cohabitation experiment” with Sheldon. Also, Howard and Bernadette are upset when Koothrappali learns the gender of the baby before they do.
Leonard and Penny must separate a quarreling Sheldon and Amy when their cohabitation does not go as planned, and Sheldon threatens to break off their relationship when Amy refuses to adhere to the bathroom schedule. Also, Howard and Bernadette find unexpected guests at their house when they decide to stay home from a planned vacation.
Penny is surprised to learn she has fans of her performance in "Serial Ape-ist" when she attends Van Nuys Comic Con with Leonard. Also, Amy hosts a Sheldon-style brunch at Penny’s apartment, and Wolowitz makes an impulsive purchase when he starts stressing out about the baby on the way.
In order to continue living with Sheldon, Amy lies to him about repairs being made to her apartment and they host an "on location" episode of "Fun With Flags" in Penny’s apartment. Also, Leonard lets Penny decorate Sheldon’s old room after he learns that she has been secretly moving Leonard’s collectibles into storage.
After a successful experiment combining their genes, Sheldon will stop at nothing to convince Amy they should procreate. Also, Koothrappali is embarrassed to tell the gang what the new woman he’s dating does for a living.
When Bert, a Caltech geologist, wins the MacArthur Genius fellowship, Sheldon is overcome with jealousy. Also, Wolowitz finds an old remote control Stephen Hawking action figure he invented.
Sheldon and Leonard try to divvy up their shared belongings, but can’t agree on anything. Also, Koothrappali and Stuart fight to be the most helpful during Bernadette’s final weeks of pregnancy.
Howard and Bernadette welcome their new baby and Sheldon and Amy celebrate Amy’s birthday.
Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible trip to Texas.
When Penny feels that Leonard is taking her for granted, she decides to go on a spa weekend with Amy. Also, Wolowitz and Koothrappali try to fix a squeaky floorboard in the baby’s room.
Sheldon uses a machine to help him identify other people's emotions, and Raj tries to understand his difficulties with women.
Leonard and Wolowitz try to distract Sheldon when he slows the progress of their guidance system. Also, Penny and Amy take Bernadette out for the night, leaving Raj and Stuart to care for baby Halley.
Sheldon and Amy have their first fight since moving in together and Koothrappali is shocked at the realities of financial independence when he stops receiving support from his father.