In the entire course of the show (which I have seen only in short clips), writers never revealed the maiden name of the character Penny (played by the utterly hot and gorgeous Kaley Cuoco — see at end). However, there is a scene where she receives a package with her last name listed as “Teller.” Supposedly it was simply added by the props people so that the label would look real. Thus, the producers of the show refused to commit to it having been the character’s name in the TBBT UNIVERSE.
SO I WILL SETTLE IT: Since they never contradicted it, the producers should be stuck with Teller as her last name. They failed to proofcheck the prop, they should be honor-bound to continuity (this isn’t the 1960s), and they could easily have had a throwaway scene where we learned Penny was doing something like that fakery — “Oh, yeah, Leonard. I use that fake name sometimes. You know full well my actual last name is…” Then, “Knock-knock-knock, Penny. Knock-knock-knock, Penny…”
“Teller” as Penny's last name is hereby established as canon by default and fan reliance.
I include the denial in the screenshot below out of fairness and courtesy. This denial is rejected for the reasons stated above.
https://tvline.com/news/big-bang-theory-penny-last-name-teller-explained-kaley-cuoco-1234883807/
Now for the important part: Kaley Cuoco proves the “dark-framed glasses make hot chicks even hotter” theory.