Young Sheldon's fall finale revealed the origins of Sheldon Cooper's (Jim Parsons) "Bazinga" catchphrase from The Big Bang Theory. In an effort to link the two sitcoms together, CBS rolls outed a crossover episode that brought Iain Armitage (young Sheldon), Montana Jordan (young Georgie) and Lance Barber (George Sr.) to the present day of the long-running parent show (via VHS tapes). Despite initial skepticism from fans, the crossover was a real success, delivering one of The Big Bang Theory's most emotional scenes of the final season.
Following the crossover, Young Sheldon doubled down in emphasizing that they're tightly connected to The Big Bang Theory by providing the backstory to Sheldon's infamous catchphrase, "Bazinga". Due to his underdeveloped social skills, the theoretical physicist has a list of quirks - from following strict bathroom schedules to imposing relationship agreements. However, nothing is as well-known and well-loved as his tagline "Bazinga", is a verbal cue that he's in a playful mood and is joking around.
Introduced in the second season of the show, Sheldon has used the term sporadically throughout the following seasons of The Big Bang Theory but he never really explained where the word came from (odd considering how much he loves lecturing people), until now. As revealed in the latest Young Sheldon episode titled "A Stunted Childhood and a Can of Fancy Mixed Nuts," the boy genius got scared that he won't be socially well-adapted due to his lack of sense of fun and mature thinking as Paige (McKenna Grace) pointed out. This forced him to go to the comic book store to get practical joke paraphernalia when he came across a tagline from Bazinga Novelty Company that says "If it's funny, it's a Bazinga," and from there, his life-long catchphrase was born.
Behind-the-scenes, Bazinga's origin is traced back to Stephen Engel, The Big Bang Theory's consulting producer and writer on its first two seasons. Apparently, Engel used the word as his own form of "I got you" in relation to a running weird inside gag that involved a half-eaten, taped-together grapefruit in the writer’s room. The tagline got so popular among the show's writers themselves that they found a way to use it on the series.
The reveal of the catchphrase's origin in The Big Bang Theory universe came a bit late, though, considering that Sheldon stopped saying "Bazinga" about four seasons ago; instead, he exclusively uses an odd laugh to indicate that he's joking or that he finds something funny. Whether there's a reason behind this switch-up remains to be seen, but in that light, it was a smart move to provide the explanation in Young Sheldon. Otherwise, it could just be a dropped a trope - similar to how the genius seemed to have stopped knocking thrice the last couple of years only for it to casually return in the middle of The Big Bang Theory's final season.
Considering its recent resurgence in Young Sheldon, it's curious if fans will see adult Sheldon utter "Bazinga" again in the remaining few episodes of The Big Bang Theory. The last couple of outings have been rough on him following the snafu with regard to his and Amy's (Mayim Bialik) study on Supersymmetry, but with that set to be resolved soon, many are hoping to see a more cheerful and less downer Sheldon.
The Big Bang Theory and Young Sheldon return in 2019.