"All words are made up words." (NCIS)

So I'm procrastinating on studying for my finals by watching NCIS with my roommate. Great show. Here's the dialogue that I just heard:

McGee: "What are we looking for?"
Abby: "Anything hinky."
McGee: "Why do use that word?"
Abby: "What word?"
McGee: "Hinky. It's a made up word."
Abby: "All words are made up words."

She makes a good point. It's interesting to think about how language comes about...but at some point and some level all words are made up words. And then it's a matter of if they become standard and common. Anyways, I thought it was interesting. :)