Did Penny (Kaley Cuoco) and Raj (Kunal Nayyar) really sleep together in The Big Bang Theory season 4? From the get-go, it was clear that the sitcom was positioning Leonard (Johnny Galecki) to be Penny's love interest, but that doesn't mean that they didn't see other people. Over the years, both have dated separately while in the flux of their own relationship. At one point, Leonard even dated Raj's sister, Priya (Aarti Mann). Penny, on the other hand, had gone out with a string of other men including Stuart (Kevin Sussman), but her weirdest affair, arguably, was with Raj.
Unlike Friends, which featured cross-dating among the New York-based gang with Ross, Rachel, and Joey, The Big Bang Theory crew fairly stuck with their partners. Howard (Simon Helberg) and Bernadette (Melissa Rauch) were the first ones to get married, followed by Leonard and Penny, and finally Sheldon (Jim Parsons) and Amy (Mayim Bialik). Raj was the only one who didn't have a stable love life over the years. Even when he asked his father's help to find a wife, things still fell through, leaving him the only single member of their group at the end of the show. Had things panned out differently, Raj could've at least properly dated Penny.
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Following their first big break-up, Leonard dated Priya while Penny ironically stayed single. While there's palpable tension between the women, they didn't speak of it, causing Leonard to spend less time with his friends and more with his girlfriend. In The Big Bang Theory season 4 finale titled "The Roommate Transmogrification," Raj temporarily moved into Apartment 4A as his sister and her boyfriend take over his place. Initially, he, Sheldon, and Penny stay in the living room, but eventually, the socially-inept genius leaves the pair to their wine. The next thing viewers see, Raj and Penny wake up in Leonard's bed together, both naked.
The idea was that they slept together, although the show ended the season with that cliffhanger, waiting until season 5 to provide answers. This left fans wondering whether something happened between the pair, but even when The Big Bang Theory picked up the year after, it didn't reveal what happened right away. In fact, Sheldon and Leonard spent a good amount of time debating what happened to her and Raj after they were caught walking out of the room in the morning. At this point, she declared that "it's not what it looks like" although she didn't elaborate on it making it more confusing.
So, did Penny and Raj really get intimate with each other? Apparently not, but not because they didn't want to. Raj explained to Penny that they "didn't have sex in the conventional sense." They were about to move forward with the deed, but Raj had a difficult time putting protection on; Penny trying to help didn't help at all, as it caused Raj to finish before even starting. Since then, this incident was never mentioned again in The Big Bang Theory. This makes sense considering that Penny and Leonard eventually got back together and tied the knot. At the end of the show, it was revealed that the Hofstadters are expecting their first child together. As for Raj, he's still holding out hope that his soulmate is out there.
Over The Big Bang Theory's 12-season run, the idea that Penny is promiscuous is often the butt of the joke - but over the course of the series, Raj technically has more partners than she does. Penny has roughly 5 confirmed partners on the show, whereas Raj has had at least 10 relationships. Ultimately, it doesn't line up with his character, who is so terrified of women that he doesn't speak around them for quite some time. Out of everyone on the show, Raj technically had the most game, and considering that even Leonard had more partners than Penny, she had the lowest number of partners out of the core cast except Sheldon and Howard. This makes the joke fall flat on its face, as Penny is often considered promiscuous when it's actually Raj who has more partners. All in all, the Raj and Penny sleeping together joke falls in line with complaints about The Big Bang Theory being rather sexist at times, and the double standard in this situation is made painfully obvious.