Warning! Spoilers ahead for Young Sheldon season 5.

An unexpected Sheldon (Iain Armitage) insult in Young Sheldon retcons a specific The Big Bang Theory season 10 plot line. The CBS' sitcom is nearing the end of season 5, but before that, the show celebrated a major milestone as it crossed its 100th episode. The outing titled "A Solo Peanut, a Social Butterfly and the Truth" had three prominent plot lines, including one that centers on Sheldon's reunion with Paige (McKenna Grace).

Sheldon was mostly sidelined at the start of Young Sheldon season 5, opting to focus on other Cooper family members. But, when The Big Bang Theory spin-off shifted the focus back on him,  most of its stories have been set at East Texas Tech, meaning, they're usually separate from what else is happening back at home. In Young Sheldon's 100th episode, viewers learned that Sheldon has been doing well at school in terms of socializing. Apparently, he has continued to hang out with his dorm neighbors, despite the snafu from the first time they started spending time together. 

Related: Young Sheldon Ruins Its Touching Big Bang Theory Finale Tribute

As Paige visited Sheldon at school, she also got to meet his friends. Despite her initial suspicions, it appears as if they really like him. In fact, one even likened Sheldon to a dog when explaining how their group essentially adopted him. Surprisingly, instead of being insulted by it, the boy genius just took it with an approving look on his face. However, this particular moment in Young Sheldon's 100th episode contradicts a specific The Big Bang Theory season 10 plot line. At one point in the sitcom, Raj (Kunal Nayyar) had to move in with Leonard (Johnny Galecki) and Penny (Kaley Cuoco) because of money problems. Sheldon tried to act cool that Raj was taking over his old room with his dog, Cinnamon. But eventually, he admitted that he hated dogs - so it's curious that he doesn't seem even slightly offended when his East Texas Tech friend likened him to a mutt. 

Young Sheldon Season 5 Trailer

Before this particular The Big Bang Theory plot line, however, Sheldon already had a terrifying encounter with a dog - although, in all fairness, he was partly to blame for what happened. As Sheldon snuck out to spend time with Penny following her break-up with Leonard, she promised him to cook spaghetti with cut-up hotdogs in it. Due to some humorous circumstances, Sheldon had to stick the sausage down his pants. That was when he encountered a dog who eventually started chasing him. The sitcom didn't reveal how Sheldon got away from the stray animal, but given his eccentricities, it isn't outside the realm of possibility that he harbored some secret grudge against the dog and all of his kind, which could potentially explain why the younger Sheldon doesn't seem to hate being compared to a stray dog. 

In any case, the way the younger Sheldon is shown interacting with his new friends is especially interesting, as it seems he has really started to like his new friends on Young Sheldon. As sweet as that is, it raises a lot of questions as to why he wasn't as friendly to the Pasadena gang on The Big Bang Theory

More: Young Sheldon Explains Missy & Mary’s Final Big Bang Theory Argument

Young Sheldon season 5 airs Thursdays on CBS.