The real target of The Big Bang Theory's satire is the arbitrary, self-serving stupidity of mainstream culture.
In the Season Four premiere of The Big Bang Theory, Sheldon (Jim Parsons) tries his charms on fellow scientist Amy (Mayim Bialik). As he puts it, he wants to procreate and give his genetically gifted progeny to the world to serve as "overlords." The date starts out badly, when Sheldon has Penny (Kaley Cuoco) give him a ride, meaning that she has to suffer through the date too.
The episode exploits their opposites-irritate chemistry. While Penny is at first amused by the idea of "Shamy," she quickly grows weary of their inappropriate questions, as they turn her dating history into a scientific investigation. While the fact that Sheldon is going on his first date ever might suggest that he's "growing up" (or maybe developing as a character), the narrative seems content, at least in this episode, just to mine the set-up for jokes.
Comically inept at any and all social interactions, Sheldon is appealing primarily because his observations cut to the heart of modern life's absurdity. As he rationally comments on events around him, he can't understand people's behaviors and motivations. If only people did behave logically, like science experiments, Sheldon wouldn't be such a fish out of water. His statements are incongruous and often hilarious, but the show's humor depends on the reactions by his peers, most of whom claim to be more well-adjusted than him, but they don't really understand the vicissitudes of existence any better than he does. Life is unpredictable and nutty, thus Sheldon's hyper-rational observations sometimes hit their mark better than the common-sense points his friends make. Because he doesn't care what other people think of him, and because his primary commitment is to logic, even taken to an extreme, Sheldon often levels a scathing satire of social norms, with witty aplomb.
The series has always presented Sheldon as a man-boy in need of protection. Sheltered by his Christian fundamentalist mother when he was growing up in Texas and now burying himself in science and science fiction, Sheldon would much rather read a comic book than interact with other people. Regarding him as a rather extreme case of how hard it can be to adapt to the pressures of the social world, his friends look after him. Roommate Leonard (Johnny Galecki) prides himself on being a more worldly academic than Sheldon is and impatiently puts up with Sheldon's persnickety and controlling ways. But they inhabit the same geek chic milieu, in spite of all of Leonard's efforts to distinguish himself from Sheldon's beyond the pale behavior.
Neighbor Penny plays the voice of common sense for Sheldon and his nerd herd. While he slams her intelligence and her waitressing job, she ridicules his prudery and bookishness. One funny bit has her teasing him when he enacts his ritual of knocking and calling "Penny" three times at her door. He insists on completing the whole ritual, even if she is already at the door. She asks him why he does that, since she just waits on the other side of the door until he finishes his three knocks. He replies that he knows that perfectly well, because he can see her shadow under the door, and then wonders whether their current conversation is pointless. He goes on to make fun of her "pointless soliloquy" later in their interaction. When faced with his obsessive behavior, Penny knows that calling him on it is pointless.
A conversation about the new robot arm fellow scientist Wolowitz (Simon Helberg) just made showcases the zingers Shenny toss at each other, brainiac versus street smarts. Sheldon tells her: "You realize Penny that the technology that went into this arm will one day make unskilled food servers such as yourself obsolete." Penny replies: "Really, they're going to make a robot that spits on your hamburger?" Sheldon to Leonard: "I thought you broke up with her. Why is she here?" Delighted when Wolowitz makes the robot arm hand her something, Penny exclaims: "That's amazing!" Sheldon rebuts: "I wouldn't say amazing. At best, it's a modest leap forward from the basic technology that gave us Country Bear Jamboree."
Often, their repartee involves Penny trying to coax Sheldon to join the social world. When Penny learns of Sheldon's new friend, whom he refuses to call his girlfriend and only communicates with electronically, she tries to get him to spend time with Amy. When he claims he can procreate with Amy through Petri dishes and surrogacy, even asking Penny if her "womb [is] available for rental," Penny persists in cajoling him to date Amy, arguing: "Think of it as getting to know the future mother of your child." Shocked, he queries: "You don't think I can achieve the required intimacy via text messaging?" As she deadpans, "probably not" and shakes her head at him, he observes: "Huh. It would appear as if the phone companies have been lying to me." Such banter makes them the show's most compelling twosome. The undercurrent to their friendship is the idea that each has something to learn from the other, his or her complete opposite.
Penny also brings a welcome emotional grounding to the gang of scientist-man-children, the rest of whom more openly see her value than Sheldon does. Penny hangs out with the guys because she is truly their friend, in spite of their vast differences in interests and worldviews. Her romance with Leonard kaput, he still carries a torch for her. While Koothrappali (Kunal Nayyar) still can't talk in front of women and Wolowitz still tries awkwardly to impress her, both men nevertheless welcome her as part of their gang, realizing that she can help their ineptitude.
While that patented awkwardness of Koothrappali and Wolowitz is sometimes reduced to too much slapstick, they are also a crack comedy team. Frequently the vehicles for elaborate situational humor, these two are constantly getting into amusing scrapes. Here, Wolowitz built the robot arm to be used to make repairs at the International Space Station, but when he tries to put it to other uses, he ends up in a slapstick situation that lands him at the ER with Koothrappali laughing at him. Their humor is often found in their attempts to fit in when they would really rather let their geek freak flags fly. Like other characters in the series, they are saved from stereotype by the warmth of their friendship with each other.
The comic commentary may be poking gentle fun at nerds, but the real target of the show's sharp satire is the arbitrary, self-serving stupidity of mainstream culture.