A person who shoves rare vocabulary words and unnecessary jargon down everyone's throats in an attempt to appear smarter. This usually just backfires, though, and they end up coming off as pretentious insecure doushebags who are trying too hard. It's cool to have a broad vocabulary --no one's saying it's not, but it's cooler to know how and when to use it.
Ted: What a splendiferous day! Isn't the day just serendipitously fortuitous?
Marvin: Slow your roll JarJargon Binks. You don't have to shove every big word you know into our conversation. You're trying too hard. Don't worry, we already know you're smart, it's why we hang out with you."
Jarjarbinks is that awesome guy from Star Wars. I haven't ever really watched Star Wars, but whatever. And, also, whenever someone says something about a jar, I like to say JARJARBINKS. Just to freak them out a little.
Joe: Today I was helping my mom clean the basement, and I accidentally dropped a jar, and it broke.
Me: JARJARBINKS.
Joe: What?
Me: Nothing. *looks around suspiciously*
Joe:No, what did you say??
Me: NOTHING. *runs away*