Idioms don’t have to make sense, and often don’t, due to semantic drift and language and cultural evolution. Indeed, one of the defining properties of an idiom is that it has meaning beyond its literal, reductionist interpretation.

Of course they make sense. Maybe they don't make sense today but they made sense back then to the people who started using the idiom. That's what I meant by cultural context. Something in their culture gave meaning to those words.

Eh, my point was that being able to use and understand idioms does not require knowledge of the original cultural context because their meaning has become uncoupled from their literal meaning. The saying could just as well be "it’s not my xyzzy of wargbl" and, if it became popular enough, would be perfectly understandable even though "xyzzy" and "wargbl" have zero meaning in English in and of themselves.

> The saying could just as well be "it’s not my xyzzy of wargbl" and, if it became popular enough, would be perfectly understandable

Yes, and it would still sound like total nonsense. I actually know concrete examples from internet culture that are pretty close to that. "I shiggy the diggy". Total nonsense yet becomes second nature after lurking certain forums for a few days.

The cultural context in the "xyzzy of wargbl" case is you made it up to prove a point. If it somehow became popular enough, fully understanding it would require the context of our conversation. It doesn't help explain the word choice since the words were made up to begin with.

Now that I thought about it, the "my cup of tea" thing must mean tea was extremely important to english speakers. Tea drinking must have been integral to their culture. They developed preferences and the concept of one's preferred tea made it into the language as a synonym for preference. Still surprising to me since this never happened to coffee or any other beverage.

You don’t need any cultural context. I’m not particularly familiar with boats, and different types of things “floating a boat” doesn’t even really make sense, but “Whatever floats your boat” never had an impact on my comprehension.

> You don’t need any cultural context.

Sure you do. At least if you're actually trying to understand what the words mean in the context they're used. I understand your "whatever floats your boat" example, including the cultural context. This tea business is completely foreign to me though.

I have no problem understanding these things. It's easy to infer meaning when they're used in actual conversation. When taken in isolation and without cultural understanding, these idioms sound like those made up sentences used for language practice.