Season 1

Leonard and Sheldon come home to what sounds like a cat wailing in the stairwell. When they realize that the wailing is coming from their neighbor Penny, they decide, for once, to keep their thoughts to themselves. Penny announces to the two physicists that she has a role in a musical and invites Leonard and Sheldon to the show. After hearing the performance in the stairwell, they make up excuses, and Leonard declines the invitation due to an alleged symposium.

Sheldon is at first astonished by Leonard's ability to lie. However, he soon becomes uncomfortable with being a part of this lie. Adding to his discomfort is the fear of what will happen if Penny finds out about the excuse, which is fairly likely after all, given that on that day no symposium was taking place. For this reason, Sheldon confesses to Penny that Leonard had lied. Yet at the same time, he told Penny another lie. Leonard had only lied about he and his cousin Leopold to save them both the embarrassment of revealing Leopold's involvement in a drug withdrawal program. Both of them really do not have time for her show since they have to go to Long Beach to assist Leopold at the support group meeting for drug addicts. Although, in reality, there is no drug addicted cousin, the four physicists decide anyway to drive to Long Beach to visit the Queen Mary.

During the drive, Sheldon is overcome by discomfort again. He believes that this lie is also too easy to see through because the cousin doesn't exists. To ease his anxiety, he asks a friend, who is an amateur actor in his free time, to play the part of Leonard's cousin Leopold.

When Penny comes over to Leonard and Sheldon's for a short visit, she gets introduced to Leo. Since the intervention didn't work, Leopold will stay with them. After a short conversation with Leo, Penny invites Leonard over for a coffee to show him the performance he missed on DVD. Since Leonard has run out of excuses, he now has to watch the musical, for better or worse, making the whole web of lies pointless. Finally, "Leopold" also starts to flirt with Penny because she was so nice to him about his alleged drug problem. Then Leonard, already very annoyed by the situation, asks Sheldon how long Leopold should stay. Sheldon answers, "He is a homeless drug addict, Leonard, He does not know where he should live. He will probably have to stay two or three weeks."