It's interesting to me how languages evolve.
We teach language in school as if there's only one correct version of a language. We study the parts of speech, nouns, verbs, adjectives, conjunctions, we diagram sentences, and generally put it all in front of young people so often some of it sinks in.
And yet languages are fluid, and change constantly. Slang terms are coined by every generation, sometimes every year. Since I teach at a college, I hear a lot of the slang, and sometimes have to pick up what it means through context. A few years ago, "amped" was being used to describe being excited about something (what other generations would have called "pumped"). These days I don't hear that being used.
Other slang terms stick around and become part of the language. Some words change their meaning entirely. For example, normally placing an "in" in front of a word makes it mean the opposite. Tractable and Intractable have opposite meanings. But Flammable and Inflammable mean the same thing. Did they once have opposite meanings too?
Lately there's been a new word popping up on the Internet as a new term meaning "blog posts". It's Bloggeries, as in "I write a lot of bloggeries about my life". It's a fun new word that isn't in wide use yet, so I'm doing my part to make it official.
And in case you're wondering how words become "official", here's an article by someone who helps do research for dictionaries.