There's a couple people in my office that seem to almost always answer their phone by saying "hola" instead of hello. There's nothing wrong with that, but I think it's funny that it seems acceptable, and no one really questions it.

Imagine if I did the same thing, but with an even more random word. Like the word, today. If I started saying vandaag instead of today, people would think I was nuts.
"Hey, what's up with you vandaag?"
"You'll never believe what happened to me vandaag."
"In vandaag's blog post, I talk about quirky things we do when talking."