Let’s take a look at what happens when Cookie Monster learns about English as it’s spoken in the UK:
There are three key things that we can learn about dialect from this video:
1. Dialects have a lot in common. This is part of what makes them dialects of the same named language rather than being considered different named languages.* Not only are they similar enough that Cookie Monster can use Hello and Good-bye in the UK, as he discusses with John Oliver, they are so similar that they don’t even comment on the similarities in the sound systems and grammar of their varieties of English that allow them to communicate nearly seamlessly.
2. It’s easier to notice differences in the words we use than differences in grammar and sound systems. There are differences in phonology and syntax between American and British English,** but Cookie Monster and John only took about the lexical differences. This is pretty common – often people talk about different language varieties in terms of what words they use for certain things (think soda/pop for American regional varieties) before they start thinking about other ways that speech might differ.
3. A lot of the meaning of different dialects comes from people talking about those differences. We like to call this metalanguage (or metapragmatic talk or metacommentary). If Cookie Monster had just corrected John Oliver about his name and left it at that, they would only have discussed similarities in American and British English. Instead, they spend much of this scene talking about differences in ways of referring to delicious baked goods. It’s because there is talk and behavior around this minor difference that it can begin to take on meaning.***
* this border gets pretty fuzzy, and could be a discussion for another time.
** not to mention Cookie Monster’s idiosyncratic English
*** discussing what kinds of meaning and how it attaches to certain kinds of people is certainly a discussion for another time. See indexicality.