Within my friend group, we talked openly, and most people do, since there's no shame to it!
However, when it came asking for help, or even just letting them know that time of the month had arrived, we made signal for it. For example, if we were in class, and one of needed a pad or a tampon, a light tap on the back and a whisper -- "The visitors are here" -- would suffice.

Other names and signals that are used are 'Auntie Flow', 'Strawberry week', 'The British are coming!' and one young lady refers to it as the 'Low' among her friends, and another just calls it 'the thingy' and points to their abdominal area.

Regardless of what you call it, you're bound to have to ask someone for a pad or tampon sometime, with or without codename.

Most people would give another person some "period protectors" if they asked, right?
Well, most people say yes, though to some, it depends on who is doing the asking.

I have been asked, and sometimes, I do have something on me, but I'm glad to say that if I don't have one handy, I probably know someone that does!

"Yeah, and I gave them one."
"I said yes, and handed them one. I always keep spares around, just in case."
"Yes, women had asked me and it was just a normal conversation. Like someone might ask you for a cigarette. Sometimes you have one, sometimes not."
"In specific situations, I have talked about it but a lot of people feel awkward about it. I make an effort to talk about it when it comes up so I can try to show others that it's completely normal."

Talking about periods shouldn't be a big deal, but sadly, in most places, it is.