The 2025 TV schedule is rolling right along, but the new shows that we get this year will be absent from regular appearances by one major figure: Sheldon Cooper. After being introduced on The Big Bang Theory in 2007 and then leading his own prequel spinoff, Young Sheldon, through that show’s finale in early 2024, the ever-popular character’s (mis)adventures won’t be shown for all to follow. This means we likely won’t be introduced to any more of his famed quirks, like his adult propensity for knocking three times. But, while we all know why Sheldon did that, I’m really loving the writer’s hilariously simple origin story for the trait.
Why Did A Big Bang Theory Writer Decide That Sheldon Should Knock 3 Times?
Of all the characters on TV with seemingly odd and unexplainable behavior, I think most fans would agree that The Big Bang Theory’s Sheldon Cooper ranks right up there. He created a roommate agreement for Leonard, a relationship agreement for Amy, once declared that he’s “too evolved” for something as normal as driving, and caused a number of headaches for those around him because of his…tendencies over the years. But, we did get a conclusive answer for Sheldon’s door knocking pattern, which was due to him believing he’d walked in on his father having an affair when he was a teen.
Young Sheldon retold this tale so that Shelly’s dad, George Sr., wouldn’t seem like an asshole (it was revealed that George and Sheldon’s mom, Mary, were actually role-playing), but the question remains: how did the writer who originally came up with his thrice-knocking technique do it, and why did he think it was a good idea? Well, executive producer/writer Lee Aronsohn gets the credit for this particular Sheldonism, and when asked by The Official Big Bang Theory Podcast host why one knock wasn’t enough for the theoretical particle physicist, Aronsohn said:
famously taped in front of a live audience, it makes sense that coming up with things that would make everyone in attendance laugh is top of mind. As written the first time we see it on TBBT (during Season 1, Episode 10), Sheldon actually knocks four times, but it was then scaled back, and either way, it’s such a surprising moment that it does “coax the audience into laughter.” He continued:
Something in me said, ‘No, there needs to be some order. There needs to be some structure.’ Reverse engineering it, yeah, I can see that it fits Sheldon to have structure. I don’t know I was thinking that at the time, it was just, ‘Wouldn’t it be funny?’
Well, for something that ended up being such a hallmark of the character (especially considering that it basically traumatized a young Sheldon and made him think way less of his father than George deserved), it is wild that the only goal was to have it be funny. As Aronsohn noted, however, not only did he hit that goal, but ultimately, it did fit the odd genius overall, so he scored on all fronts!