The Big Bang Recap - Live Updates of "The Cohabitation Experimentation"

The episode opens with Amy telling Penny and Leonard how her apartment flooded, forcing her to move out for five weeks. Penny says that Amy can move into their place. Conveniently, this will let Penny and Leonard actually live together without a roommate, and let Amy "move in" with her boyfriend. When they reach the apartment, everyone's smiling...which of course freaks Sheldon out.

Sheldon isn't too happy with the idea of change, and is worried that living together might "ruin the romance". But Amy tells Sheldon to approach the temporary cohabitation as an experiment, but Sheldon doesn't really consider the idea until Leonard brings Star Trek into the equation. However, Sheldon wants to treat living together "as an experiment", so Penny says Amy and Sheldon can live in her apartment, while Penny and Leonard will stay at their place. Sheldon agrees to the experiment, but warns Amy that like Star Wars, this experiment could get cancelled prematurely.

Raj, Bernadette, and Howard return from Bernadette's latest OB/GYN trip (Raj accompanies them on visits). Howard and Bernadette ask if it's silly not to know the sex of the baby, but Raj reveals he looked at Bernadette's file and knows whether they're having a boy or a girl.

Sheldon asks Penny for advice on how to live with their significant other, while Amy asks Leonard the same question. Penny gives Sheldon a lot of practical advice, but Leonard's advice is more like care instructions for a small animal.

Later that day, Amy points out to Sheldon that they're going to be sharing a bed together, which is uncharted territory. Amy shares that she's nervous about it too, and points out that they don't need to have sex together...at least at first.

Penny gives Amy the keys to her place, and Leonard makes a crack about Sheldon going where "no man has gone before". Sheldon replies that it's Penny's bedroom, so plenty of men have gone there. Once Sheldon and Amy walk into their apartment, they immediately hear Leonard and Penny celebrate outside.

Sheldon asks Amy which side of the bed he wants, but Amy knows that Sheldon cares more about these things and tells him to choose. Sheldon weighs the pros and cons of each side, and finally chooses when Amy gets angry.

That night, Bernadette asks Howard if its silly that Raj (and probably everyone on the Internet) knows the sex of the baby, but they don't. Howard compares knowing the sex (and pregnancy in general) to a magic trick, which is a terrifying comparison. We also learn that Howard wooed Bernadette by pulling a string of rainbow hankies out of his crotch.

Meanwhile, Sheldon and Amy's first night together gets off to a roaring start as Sheldon listens to Amy go through her nighttime routine in disgust. Amy asks if they could snuggle, to which Sheldon asks if they can build a pillow wall between the two.

Once Sheldon's officially in bed, Leonard and Penny try to figure out what to do for their first official night alone. Leonard decides to celebrate by dancing in his underwear and eventually gets Penny to jump in. We then get a montage of how everyone is spending their night. Sheldon is unsurprisingly hard to sleep with, Bernadette and Howard call Raj several times to ask about the sex of the baby but hang up each time, and Leonard eventually crashes and burns when trying to do the worm. Amy's attempts at cuddling also ends with Sheldon butt bumping her out of bed.

The next morning, Amy tells Penny that she didn't get any sleep, because it turns out that she slept on the floor. Amy wants to end the experiment, but Sheldon appeals to Amy's scientific side to keep going. This leads to a scientific diss battle between the pair and the two storming off to go make out back in their apartment.