The United Kingdom of Great Britain and Northern Ireland, for long. Straddling a group of islands in the North Atlantic on the north-western flank of the European continent, and tenuously connected to France and therefore mainland Europe by the Channel Tunnel.
In the context of The Big Bang Theory, this is the native country of Professor Stephen Hawking, a man reverenced by Sheldon Cooper and who has made several cameo appearances on the show. It is possible that Leonard Hofstadter's starting point to his North Sea expedition would have been through a port on the east coast, possibly a university city such as Newcastle or Hull. Great Britain is also the home of the world-renowned universities known to the native British as "Oxbridge" - a catch-all conflation of "Oxford and Cambridge". Rajesh Koothrappali attended a Cambridge college in his earlier academic career, possibly one where Hawking taught.
Great Britain is also the home of several seminal sci-fi shows reverenced by the Caltech gang: Doctor Who, Red Dwarf, and the Supermarionation animations of Gerry Anderson. It is also the point of origin of Douglas Neil Adams, who launched H2G2 - The Hitch-Hiker's Guide to the Galaxy - in at least six different media formats. Neil Gaiman, of Sandman fame, is British, as is his friend and collaborator Sir Terry Pratchett, of Discworld fame. J.K. Rowling's student wizard Harry Potter was also born here, as a very British reimagining of the boarding school story once so popular. From Penny's point of view, it is the home of one of her favourite bands, Radiohead.
In the "real" world, The Big Bang Theory is screened in this country by the Channel Four group, and on any given day re-runs can be viewed on Channel Four, E4, and More 4. E4 has the franchise to perform first-screening of new seasons, and is currently (in April 2015) showing Season 8 some nine weeks behind the USA.
American English as used in TBBT and British English equivalents:
- Afrin: deocngestant nasal spray referenced in The Fermentation Bifurcation Known in GB as Vicks Nasal Spray.
- Moonpie: In the sense of a sweet biscuit, a Wagon-Wheel.
- Instant Ramen: a Pot Noodle.
- Three hundred pounds (a guess at Debbie Wolowitz' weight): 21 stone four pounds or 136kg.
- Thin Mint - marketed in the UK as an AfterEight
- Two hundred pounds (the cosplayer Raj and Howard have intercourse with, at ComicCon) - fifteen and a half stone or 91kg.
- Community College: "New University"
- "Dove Bar" - in the UK, Dove is a bar of soap
- "Dove Bar" (US) - Galaxy Chocolate bar (UK)