Yesterday afternoon, two of my female co-workers were looking online for a get-well gift for a male co-worker. Another male co-worker told them: "Guys, guys, you're buying for a guy, not buying for a girl."
I thought that was a perfect demonstration of the two common idiomatic uses of guy. Neither the guy who said it nor the (um) guys who it was addressed to saw anything unusual about it.
> the (um) guys who it was addressed
Surely you meant to say “the (um) guys to whom it was addressed”?
Nadya, in her informal speech, has recently started using “lady” as an affectionate address for anyone. It started with her (tall, athletic) younger brother and has spread outward from there. I’m not aware of her ever making a decision about it, it just crept in organically. However it happened, it’s fun to watch people react to it.
“Sister” is another good one. Me, I just refer to everyone up to and including my friends’ parents as “kids”.
I use “dude” for pretty much everyone.