Warning! SPOILERS about Young Sheldon season 6 ahead.Sheldon is known for his rule-following to a fault attitude in both The Big Bang Theory, but one detail in Young Sheldon season 6, episode 1 goes against Sheldon’s acknowledgment of his relationship with Penny in The Big Bang Theory season 1. Sheldon always found comfort in routines both in Young Sheldon and its CBS parent series since he often employed strict schedules and agreements to live peacefully with others in both sitcoms. Sheldon’s bathroom schedule and roommate and relationship agreements are famously and consistently used in both shows. They always let Sheldon steer clear of ambiguity, but that wasn’t always the case in TBBT.

Young Sheldon season 6, episode 1 had Sheldon go out of his way to find a definition of the relationship that linked Mandy to him and Missy, deciding on the moniker of “niblingo” because he needed to find the right nomenclature before continuing hanging out with Mandy. However, despite both Young Sheldon and The Big Bang Theory describing Sheldon as a stickler for rules and conventions, he didn’t always approach social situations that way. The Big Bang Theory season 1 included plenty of social outings where Penny was included by Leonard, Sheldon, and the others, and Sheldon never felt the need to define their relationship, despite being friendly toward Penny.

Sheldon Needs To Clarify His Connection To Mandy With The Niblingo Moniker

Emily Osment as Mandy and Iain Armitage as Sheldon Cooper in Young Sheldon season 6 episode 1

Besides all the issues the community had with Mandy and Georgie’s child and their relationship not involving a marriage in Young Sheldon season 6 that impacted the Coopers, the inability to define the relationship between Missy and him and Mandy had Sheldon thinking. Sheldon coming up with “niblingo” obviously provided comic relief in Young Sheldon season 6, episode 1, but it was also particularly illustrative of Sheldon’s requirements. After all, Mandy and Georgie deciding to be both involved in raising their child without having a relationship went against the conventions that could have helped Sheldon define their familiar rapports, putting Sheldon in a tough spot to identify.

TBBT's Sheldon Accepted His Relationship With Penny Without Naming It

Kaley Cuoco as Penny and Jim Parsons as Sheldon Cooper in The Big Bang Theory season 2

While Sheldon feeling the need to clarify his connection to Mandy fully makes sense based on his inclination for order, it wasn’t how Sheldon always classified his social connections with others. Indeed, The Big Bang Theory season 1 had Sheldon, Leonard, Raj, and Howard often include Penny in their get-togethers and even them attending parties Penny hosted. Not only did Penny and Sheldon never sit down to define their relationship, but when Penny offhandedly asked Sheldon to keep her secret from Leonard as her friend in The Big Bang Theory season 2, episode 1, Sheldon was just as baffled by her assumption about social conventions as about them being friends.

Despite Penny going to Sheldon for advice on what to do when dating Leonard, and Leonard doing just the same but for Penny, highlighting how both behaved as friends with Sheldon, Sheldon never even considered Penny to be his friend before The Big Bang Theory season 2, episode 1. Penny often showed the same understanding toward Sheldon. Nevertheless, Sheldon never sat down to define them as anything more than acquaintances, just accepting Penny’s definition of their friendship as such. Having Sheldon fixate on his connection to Mandy in Young Sheldon season 6 thus fully contradicts how he and Penny came to be friends in The Big Bang Theory.