I might buy that “you dudes” could be grammaticalized as the second person plural in some “dude”-heavy dialect, but never “dude” by itself. Nobody is saying that “guys” by itself forms the regular second person plural in some USian dialects of English but rather that “you guys” is. Part of the evidence that “you guys” has been grammaticalized as such is that it is what regularly fills the paradigm for those speakers but also that there are typically weird constructions for the second person plural possessive that can’t occur with something like “you athletes” or “you Ohioans”.
- Can I borrow your guys’ phone? (Napoleon Dynamite)
- *Can I borrow your athletes’ phone?
I suspect that it might actually be the case that some speakers have:
- ?Can I borrow you dudes’ phone?
or - ??Can I borrow your dudes’ phone?
I speak a very “dude”-heavy dialect but 4 seems very questionable to me unless it means “Can I borrow the phone of your dude, i.e. the dude you brought into this situation or your boyfriend?” It doesn’t seem like it can mean “I can I borrow the phone that belongs to all you dudes?” 3. on the other hand, seems surprisingly good to me.
This doesn’t get around the fact that “dudes” by itself as a vocative as in “Dudes, can I borrow your phone?” (or “It’s Wednesday, my dudes.”) is not serving as a second person at all. It is a vocative in the same way that “John and Susan” in “John and Susan, can I borrow your phone?” wouldn’t be something you would put in the pronoun paradigm. Dude, I’m not even sure it is really supposed to be vocative at all but rather some other sort of discourse marker like “so” or “anyhow” that kind of serves as an intensifier, i.e. “Dude, where’s our car?”.
