Original air date: 10/01/2007 Runtime: 21:02 min. After Leonard tries to do a favor for Penny, Sheldon ruins the plan. Leonard volunteers to sign for a package, hoping to make a good impression on Penny. However, when he involves his obsessive-compulsive roommate, Leonard sees his attempt at chivalry go horribly awry.
Original air date: 10/08/2007 Runtime: 21:58 min. Leonard is depressed to learn that Penny is dating someone. As a result, encouraged by his friends and fellow scientists, Leonard actually summons the nerve to ask a woman out on a date. SARA GILBERT ("Roseanne") guest stars as Leslie.
Original air date: 10/15/2007 Runtime: 20:35 min. After being fired from his job, Sheldon attempts to explore the "dreadful" life beyond physics. But his initial thrill of shopping with Penny devolves over time to him weaving ponchos as a shut-in, forcing Leonard to call on Sheldon's mother, Mary (LAURIE METCALF - "Roseanne").
Original air date: 10/22/2007 Runtime: 20:06 min. After sensing that his pursuit of Penny isn't going anywhere, Leonard agrees to an unexpected sexual encounter with fellow scientist Leslie Winkle (recurring guest star SARA GILBERT). The one-night stand throws Leonard and Sheldon deep into uncharted social waters.
Original air date: 10/29/2007 Runtime: 20:57 min. The socially stunted guys are nervous when Penny invites them to a party she's hosting. But they are ecstatic to find out that it's a Halloween party and enthusiastically don their respective nerdy costumes, which unfortunately fail to impress Penny's brutish ex-boyfriend. Afterwards, Koothrappali experiences the unexpected with a partygoer, Cheryl (ERIN ALLIN).
Original air date: 11/05/2007 Runtime: 21:09 min. When Wolowitz seduces Penny's friend and ends up sleeping with her in Penny's apartment, Penny sleeps on Leonard and Sheldon's couch. Meanwhile, with Wolowitz occupied, the guys discover that they are without a fourth member of their group. In desperation, they ask Penny to join one of their two-person Halo teams.
Original air date: 11/12/2007 Runtime: 20:06 min. Koothrappali becomes overwhelmed when his parents arrange a blind date for him, but he discovers he actually can talk to a member of the opposite sex after a few drinks. However, complications arise when his beautiful date shows more interest in Sheldon.
Original air date: 04/14/2008 Runtime: 20:02 min. When Leonard and Sheldon meet a 15-year-old physics prodigy, Sheldon is distraught that this boy genius is younger and smarter. In an attempt to restore a sense of purpose, the boys come up with a solution to derail the young prodigy's research.
Original air date: 04/21/2008 Runtime: 21:38 min. The guys decide to compete in the university's Physics Bowl, but since Sheldon's only focus is to prove his mental superiority, the guys kick him off the team. To take his spot, they enlist his nemesis Leslie Winkle (recurring guest star SARA GILBERT).
Original air date: 05/05/2008 Runtime: 21:50 min. Leonard, Wolowitz, and Koothrappali all become smitten with Sheldon's twin sister, Missy (guest star COURTNEY HENGGELER), and Leonard devises a plan to eliminate his rivals. The plan backfires, however, when Sheldon declares he will decide whom his sister dates.
Original air date: 05/12/2008 Runtime: 19:45 min. When Penny learns that Leonard doesn't celebrate birthdays, she attempts to throw him a surprise party, she is sidetracked by Sheldon, however, who unexpectedly gets to live out one of his greatest fantasies at an electronics store.