Speaking the native language

There is a world of difference between learning to speak a language, and learning to speak it like a native speaker. The nuances, the subtleties of expressions, the colloquialisms - they work together to conspire against the everyday learner. Which has set me thinking about the intuitiveness of languages. As more than just a mode of communication, but rather as an overall reflection of a culture and way of life.

One of my colleagues was kind enough to agree to help review my Spanish homework today.

"So this sentence here," he said. "Can you read it out to me?"
So I did. He grinned.
"What? What?! What's wrong with it???"
"Nothing.... well, it's just that... that's not the way I would say it."
"What do you mean?" I asked. "Is it grammatically incorrect? It's that word 'al' over there, isn't it? That's what's made it wrong, I knew I shouldn't have put it there."
"No, no, it's not the al, that's fine," he soothed. "It's just that, if you said it like that, people would understand you, but they'd also know you were learning Spanish as a second language."
He smiled an inside-joke kind of smile.

"Why, how would you say it?"

And he said something totally different, not even close to what I had said.

He must have seen my crestfallen expression, because he continued hurriedly, "Well, there's nothing wrong with the way you said it. It's just that locally people would say it differently."
"Why? How would I know how to say it the right way?"
Shrug. "It's just something you know."
"Dammit!" I exclaimed. "So how will I learn how to say it right?!"
Shrug.

"So at least the grammar was correct, right? I mean, it's just the colloquialism and I can't really help that..."
"Well," he responded, "that was for that sentence. But with this sentence here..."