Alan tries to hire his ex-wife's lawyer to help him win custody over the dog he and Kandi shared.

Charlie dates a woman whose personality and life are like his mother's.

Sheldon goes behind Leonard and Howard's backs.

The gang flashes back to 2010.

Sheldon and Amy develop a system for wedding planning.

Ursula dumps Joey but doesn't plan to tell him, so Phoebe disguises herself as her twin to break the news. Rachel cajoles Monica into trading identities so she can use Monica's health insurance for a sprained ankle.

Rachel interviews for a job as an assistant buyer at Saks Fifth Avenue. She also sees another side of the usually docile Ross when the girls face the boys during a not-so-friendly game of poker.

The gang searches frantically for Marcel, who slipped out of the apartment while Rachel was baby-sitting him. Rachel, who doesn't know that Marcel is an illegal pet, ends up calling Animal Safety.

Rachel and Barry start dating again which is slightly awkward because he's now engaged to Mindy. Chandler goes nuts when a woman he likes won't return his calls. The friends discover someone is spying on them.

Alan tries to hire his ex-wife's lawyer to help him win custody over the dog he and Kandi shared.

Alan is overjoyed by the prospect of Judith remarrying as he would no longer have to pay alimony. When it looks like the marriage might derail due to Jake's dislike of his mother's fiancé, Alan asks Charlie for help.

Charlie dates a woman whose personality and life are like his mother's.

Sheldon goes behind Leonard and Howard's backs.

The gang flashes back to 2010.

Sheldon and Amy develop a system for wedding planning.

Ursula dumps Joey but doesn't plan to tell him, so Phoebe disguises herself as her twin to break the news. Rachel cajoles Monica into trading identities so she can use Monica's health insurance for a sprained ankle.

Rachel interviews for a job as an assistant buyer at Saks Fifth Avenue. She also sees another side of the usually docile Ross when the girls face the boys during a not-so-friendly game of poker.

The gang searches frantically for Marcel, who slipped out of the apartment while Rachel was baby-sitting him. Rachel, who doesn't know that Marcel is an illegal pet, ends up calling Animal Safety.

Rachel and Barry start dating again which is slightly awkward because he's now engaged to Mindy. Chandler goes nuts when a woman he likes won't return his calls. The friends discover someone is spying on them.

Berta drags Charlie with her when she confronts the father of her pregnant daughter's baby. Meanwhile, Alan reveals a secret fetish.

Alan suffers about of insomnia and a visit to his psychiatrist reveals the cause of Alan's sleepless nights is his jealousy towards Charlie and his own inability to glide through life.

Charlie gets tired of Alan's mooching and reaches the breaking point during the brothers' double date. Meanwhile, Jake is left home alone for the first time.

Sheldon plans a special themed dinner for Amy's birthday.

Sheldon and Amy use science to choose Best Man & Maid of Honour.

Penny helps Sheldon figure out his next scientific move.

When Monica's credit card is stolen she ends up making friends with the thief. Ross discovers Marcel has reached sexual maturity and needs to be with his own kind, so he tries to get him into the "Harvard" of all zoos.

After losing his virginity to her, Monica's boyfriend reveals he's a high school senior. Rachel has erotic dreams about Joey & Chandler. Whilst temping, Phoebe discovers no one at Chandler's office likes him anymore.

Carol goes into labour and Ross and Susan can't stop bickering over who gets to help more. Rachel flirts with an OB/GYN who has a love-hate relationship with women's private parts and Joey ends up assisting a birth.

During Rachel's birthday party, and while Ross is in China, Chandler lets it slip that Ross is in love with her. Joey's girlfriend wants to sleep with him but his participation in a fertility study is preventing this.

When Monica's credit card is stolen she ends up making friends with the thief. Ross discovers Marcel has reached sexual maturity and needs to be with his own kind, so he tries to get him into the "Harvard" of all zoos.