So, I have a deep and pervading love for anthropology, and an even deeper love for applying anthropology/sociology to fantasy worlds.  Because of this, I love the trope of Hobbits having their own secret language that no one knows about. However, the idea of that language being an even more closely guarded secret than Khudzul just never seemed to really mesh with their otherwise fairly open and carefee culture.  The idea of going to great lengths to hide their language just never really seemed to mesh with hobbit sensibilities to me, even if they do have at least a few isolationist tendencies.  They just don’t seem very invested in the idea of secrets.
But then I thought of something even better.
The Hobbits do have a language that no one knows exists.  It’s mostly formal, used in things like traditional sayings, speeches at weddings or funerals, well-wishes offered at births (or birthdays), often found in legal papers, etc.  They grow up speaking it and common, often interchangeably and the amount it’s spoken in each household varies, some use it near exclusively, some use mostly common, some use them equally.  (I imagine Bilbo’s used mostly common, and his parents used the traditional language when they really wanted to emphasize what they were saying)
Here’s the catch.  It’s not actually a secret.  There’s nothing forbidden about revealing it or teaching it to outsiders.  Hobbits would be happy to explain it to anyone who asked.  It’s just a thing that they have.  However, there are two reasons that no one else knows about it.  First is that outsiders just aren’t likely to be involved in anything that would expose them to it in the instances it’s traditional or required.  They’re not hobbits, so they’re not entangled in hobbit law, or going to hobbit weddings, or hobbit funerals.  Some will go to hobbit birthdays because those are the the kind of celebrations everyone gets in on, or the reception for hobbit weddings for the same reasons.  But while there are traditional well-wishes in the language, outsiders aren’t really there for the big long speeches in it.
The second, biggest reason no one knows though, is that it is RUDE to speak a language your guest doesn’t understand.  In order to be polite and not exclude the big folk, hobbits switch to common whenever they’re in earshot of someone who’s not a hobbit.  It’s only polite after all!
And so the language of the hobbits is the best kept secret in middle earth, not because it’s a secret at all, but because of hobbit manners.
