Whether Sheldon Cooper is young (Iain Armitage) or slightly older (Jim Parsons), the central character of “The Big Bang Theory” and “Young Sheldon” has his share of eccentricities. In fact, much of his personality and daily routines revolve around these, to the point that other characters must learn to bend around his schedule or risk serious antics. Some of the character’s peculiarities are accepted for their face value, but “Young Sheldon” also drops some hints on how certain of his “Big Bang Theory”-era traits came to be. 

Adult Sheldon’s notorious obsession with his bathroom schedule may finally get an explanation in “Young Sheldon” Season 7, Episode 4, “Ants on a Log and a Cheating Winker.” In the episode, young Sheldon is shocked to find out that he now has a roommate, Evan (Motoki Maxted). Among other things, this creates some friction when Sheldon realizes he now has to share the bathroom, and he ends up disinfecting the entire room after Evan. This is when Sheldon realizes that the bathroom isn’t freely available to him, and it may well mark the moment when he starts developing his infamously strict bathroom schedule. However, this isn’t the only reason the episode is a pivotal point on the entire “Young Sheldon” timeline. 

“Ants on a Log and a Cheating Winker,” like “Young Sheldon” episodes tend to do, covers several plotlines. Apart from bathroom issues, Sheldon clashes with Evan about the concept of cheating in video games. The young protagonist also has to deal with a long layover flight and the discomforts of not just one but two babies. First, one is crying on the plane, and then Sheldon discovers that Georgie (Montana Jordan), Mandy (Emily Osment), and baby CeeCee have taken over his room, with the latter disturbing his sleep. In one non-Sheldon plot, Mary (Zoe Perry) visits Meemaw (Annie Potts) at Dale’s (Craig T. Nelson) home.

Interestingly enough, the episode might hint at the beginning of Sheldon’s long-standing bathroom schedule, but it also provides a new reason for another prominent habit of his. Sheldon is famously fond of always knocking on doors exactly three times, and he explains on “The Big Bang Theory” that he learned to do this after inadvertently walking in on his father cheating on his mother. “Ants on a Log and a Cheating Winker” reveals that George Cooper Sr. (Lance Barber) wasn’t actually cheating on Mary during this unfortunate incident. Instead, the pair was indulging in a bit of role-play, and Mary was wearing a German Oktoberfest-themed costume when Sheldon walked into the room after a single knock. 

For more on CBS’ “The Big Bang Theory” prequel, be sure to check out the reason “Young Sheldon” ended after Season 7 and “Young Sheldon” actors who played different characters on “The Big Bang Theory.”