Flibbertigibbet

Well, if you want to get even more persnickety about it...

If "second" is truly used here to modify only "annual", then its called an adverb. (I've never heard the term prepositional adjective, but adverbs modify verbs, adjectives and other adverbs. Adjectives modify only nouns.)

But I will submit that it is modifying the noun, "BBQ", and is thus indeed an adjective. However, in that case, it requires a comma to separate it from the rest of the clause, i.e. should be "second, annual, summer BBQ". (This is based on my memory of a rule that I cannot manage to locate a reference to, so now I'm unsure of myself.)

In any case, to answer your explanation of word order changing meaning, I do not believe that that makes "second" modify "annual" instead of "BBQ". Rather, I would say (again, based on my judgment alone, not by reference to some linguistic authority) that the word "second" modifies the noun-clause (a concept I just made up, but I suspect I am not its originator) "annual summer BBQ", and likewise that "annual" modifies the noun-clause "summer BBQ".

To support my claims, let me give two examples to ponder:

"She bit into the shiny, red apple."
"He lifted the second heavy crate."

In the first example, the order of "shiny" and "red" makes no difference to the meaning of the sentence, so it is true that this supports your case that switching word order is a good way to determine proper reference. However, in that case, a comma is required (so I was taught in grammar school) to separate the two adjectives.

In the second example, I'm not as unshakably certain. I'm trying to imagine how I'd expect to read it in any of my books, and I just can't see the comma. However, word order does indeed make a difference. A second heavy crate implies that the first was heavy, too, whereas a heavy second crate would imply that the first was not heavy. However, the word "second" clearly modifies the noun, "crate", and not the other adjective, "heavy", because a "second crate" would make sense, but a "second heavy" would not. (So maybe a comma to separate them is proper?)

Anyway, I think that your GM was either trying to be cute to rile the troops (something I have seen charismatic managers do), and wasn't seriously advancing his claim, but rather just defending a point to make for lively conversation; or else he was being an ass because he is obviously wrong. Language is primarily for organizing concepts, and secondarily for communication. The rules exist to serve order, not to obscure referents. It was clearly your third BBQ and to have a language that insists on using base-0 arrays (to borrow from computer programming concepts) rather than base-1 arrays is just lame. (And personally, I don't even thing it is justifiable in late-generation, high-level programming languages, either.)

"The Sabbath was made to serve Man, not Man to serve the Sabbath."

Mister Bookworm tells me that he was just being descriptive when he said "prepositional adjective."

He said a bunch of other stuff, too, but it was very complex and I can't possibly pretend to understand all of it right now.

I should have said, also, that I *do* like the term "prepositional adjective". I'm not really clear on the cognitive or linguistic need to have adjectives describe only nouns and adverbs describe everything else. Maybe we could classify prepositional adjective as a species of adverb?