There are certain jokes which don't rely on a punchline so much as on the feel of language -- wordplay that doesn't strike us as funny because of clever double meanings but because it just... has a certain feel, for lack of a better word. "Jokes" might be the wrong word, too. Nothing so formal as that. Like treating plurals as singulars, at least when they are plurals not formed with a simple -s. Like Tad Williams' facebook status update the other day, on how children are crazy, and "thank goodness I was never a children."
Or the phrase under consideration today, the frequent comment that so-and-so "is good people." This sort of informal not-exactly-a-joke may be overused, but unlike a true joke it doesn't seem to decay with use. It's sort of insinuated its way into our language, far as I can tell. In doing so it doesn't mean the same thing as saying so-and-so is "a good person." It has hardly any connotation of morality; the connotation is all of wholesomeness and appealingness. Or just appeal, if you prefer to keep your nouns simple instead of adding a nounizing morpheme to their adjectival forms. But that sounded too much like the verb for my purposes here. Anyway. So you see, "good people" even acts very much like a one-word adjective, despite being formed out of what's ostensibly one adjective and one noun.
This is why it makes perfect, perfect sense that the other day after making oatmeal cookies I often found myself thinking, as I ate them, "Oatmeal cookies are good people."
This is not an example of true language change however -- I highly doubt the above example will make its way into widespread use. The origin is too transparent at the moment -- one's brain can easily and subconsciously follow the change of meaning between "a good person" and "good people" in the original context of describing one person; using it for inanimate objects jars the brain back to superconsciousness, and most people who aren't fond of analyzing language would find it extremely crazy instead of realizing how much sense it makes.
It does sort of fit into the overarching reason for language change -- to make something either easier to say or to understand. I mean, there's this very specific connotation that has come to be signified by the words "good people." I wanted to apply it to my oatmeal cookies. That was the easiest way to express the intended connotation. But alas, for the reasons given in the above paragraph, I cannot. I must bow to the oft-said (in my linguistics classes), "speakers of languages are lazy." It's true in making me want to say "oatmeal cookies are good people," and it's true in preventing me, for I can hardly expect sufficient English speakers to become language analysts and agree with me that the above statement makes sense. It is not easy to understand. A pity. At least they can't prevent a blog post.
Yep. That's my answer and I'm sticking to it. And yes, I was this way before I took linguistics classes. I just didn't have as many resources at my disposal. It's harder when you have to build your resources from scratch.