I would bet that:
More people know who Ludacris (the rapper) is than know what the word “ludicrous” means.
More people know what a ShamWow is than know what a chamois is.
Any other examples of this?
Does “ginormous” count? I really hate that word. According to Wiktionary, it’s been around since 1986! I only became aware of it a few years ago. We already have two perfectly good words, gigantic and enormous, that express what this neologism clumsily does.
Yeah but everyone knows what “gigantic” and “enormous” mean.
I would bet money that the average person in America is more likely to know what a ShamWow is but NOT what a chamois is, than to know what both are.
What a chamois is or what it’s called?
Yeah, I’d definitely say that “ginormous” is a humongous waste of dictionary space.
What is a ShamWow? I have no idea.
I know what a chamois is. I might not know how to pronounce it. I always heard it as “shammy” (not “Shamwow”) but I figured if you were speaking actual French it would a bit different (still not “shamwow”).
I seriously doubt either is true. There may well be some music fans who are more likely to talk about a (I assume) popular rapper than use the word ludicrous in a sentence, but that doesn’t mean they don’t know what it means. Ludicrous isn’t that obscure a word, and I think you’re seriously underestimating the millions of English speakers who know nothing about rap (and the intelligence of those who do).
And I’ve never even heard of ShamWow, but looking at the website, I see a big headline saying “It’s like a chamois…” and what I assume is a TV ad with an annoying shouty man telling me that it’s “like a chamois.” So I assume that anyone who’s heard of ShamWow will at least have heard of chamois, even if their only knowledge of it is “what a ShamWow is partly like” (though I can’t imagine there being many like that – there’s no point in saying “X is like Y” if no-one’s heard of Y).
Gay? Fag? Weird? Computer? Lame? Cool? Awesome? Tubular? Rock?
guesstimate
I hate that “word.” I’m sure many lawyers do.
decimate
ironic
literally
I see (and appreciate) what you did there…
Conspiracy Theory
It doesn’t just mean a theory of a conspiracy it means a hokey half-baked idea regarding a vast global conspiracy.
Really? I’ve never heard of Ludacris or ShamWow. I know what ludicrous means and what a chamois is. I also think that most people I know at least know what ludicrous means.
This message board is not representative of the population of America, in any way, shape or form.
The majority of the people in this country have pretty lowbrow tastes in my opinion, and are willfully ignorant of culture, language, literature, science and history. The majority of people spend a hell of a lot of time watching TV, much more than they spend reading.
This needs to be prominently displayed somewhere, I think. It’s that important a point.
I’m not sure the OP’s suggestions are valid examples of the thread title since they’re both proper nouns, rather than eponyms, so do these even qualify as new words entering the collective lexicon?
**Bearflag’s **suggestion of *literally *is a good example since in the past it actually meant, you know, like literally literally and now it applies to –not- as in someone nonsensically proclaiming: “I literally fell to pieces. Literally.” And the original meaning of *decimate *also seems to have gone the way of the dodo. Also I like how the phrase Midas Touch is used as a positive quality whereas anyone who read the myth on which it is based understands that this quickly became a punishment for greed.
But what bugs me about word blends such as ‘ginormous’ is the need to think these need to be included in updated dictionaries –as if anyone with two working neurons couldn’t figure it out- and the recent trend of creating these clunky and witless word amalgams.
bromance / staycation / frenemy
They’re not clever, you don’t appear hip when using them and instead come across as mindless nitwit blindly following the latest doofus-trend in an unsuccessful attempt to fit in.
It makes my head spin. Literally.
Since when did the SDMB have a monopoly on culture, language, and literature? Those are living, evolving things and the “majority of people in this country” have every right to live and speak as they see fit; pop culture has as much – if not more, by virtue of sheer popularity – legitimacy as highbrow, elitist tastes.
Just as you don’t speak Old English or write like Shakespeare (thank God) anymore, so too do the masses continue to update their lexicon and lifestyle. Nothing wrong with that.
Now when and comes to science and history, on the other hand… I weep for this country 
The whole “using the word Bro to denote a close male friend or someone you wish to appear friendly with” thing annoys me, actually.
I think we can concede that we’ve lost the war against the word “Expresso”, and that words like “Paradigm” and “Synergy” have become empty, meaningless buzzwords.
Also, the words “Gay” and “Queer” have changed from their original meanings (Meaning “bright, colourful, and happy” and “a bit odd”, respectively) to their modern definitions.
Fair enough, I’ve never been to the USA and so can’t comment on that. It may well be a fair comment for the use of English in the US.
I am going to Vegas on Friday though!!! Maybe I’ll report back with my findings after that. 
Pete Townshend used it in 1972 in the liner notes of Who Came First (spelled “gynormouse”).
Yeah, the SDMB is littered with a bunch of gaming, pastie-white social misfits who should loosen up and use words like ‘ginormous’. The number of “I can’t get laid” threads would literally go down exponentially. It’d be a quantum leap, and all of your sex lives would experience meteoric rises.
ETA a smilie.