One of the most enduring stereotypes of Hawaii, Polynesia and the Pacific islands in general is grass skirts. To what extent is this real and to what extent is this tourist hype and romanticism? For example, would you expect to see locals out and about on their daily business wearing grass skirts, or is this stuff only worn at cultural festivals and tourist traps?
I’m more interested in the history of the coconut bra. 
ISTR that the coconut bra was mostly seen on board US Navy vessels during WWII. Also, grass skirts, and mop-heads used as wigs.
Today, I feel 100% confident that this is only seen at cultural festivals and tourist traps.
I mean, even in the most primitive native villages in the most backward places on the planet, you see people wearing clothing made of cloth (according to the pictures one sees in National Geographic).
The only people you’ll see wearing (something that looks like) grass skirts are woman doing the hula. I can’t find a very consistent history of the grass skirt. Here are some references:
The grass skirt is for hula dancing. Originally, hula costumes comprised a variety of skirts, the most common being a wrap skirt of kapa, a cloth made from bark. The hula was suppressed by Christian missionaries and their converts, and when it was revived, the grass skirt dominated, probably introduced by laborers from other islands, and now made popular by tourism and Hollywood.
While there is probably someplace where grass skirts were common daily wear (maybe Kiribati?), I feel confident that there is no such place today.
Almost certainly invented by a Westerner. Before the missionaries came along and tried to convince them how immoral it was, Polynesian women generally didn’t cover their breasts at all.
Yeah, I’m pretty sure they aren’t really historically accurate. It’s probably a relatively modern invention mostly for the benefit of tourists. 
I can’t really remember what the women wore when I was a kid in PNG.
But lots of the older blokes used to wear leaves at the back: just snap a clean small branch off the bush every day,
I presume PNG is Papua New Guinea.
Other than ceremonies for us tourists, I didn’t see any worn in Fiji. I did see people wearing sulus. I have a simple one as a souvenir.
Also, didn’t see any in Micronesia, when I visited Palau and Chuuk.
(why yes, I am a scuba diver…what gave it away?)
If you’ve heard of a place, its inhabitants have been wearing machine-made cloth since the 19th century.
About the only thing I have to add is that cartoon cliche’ “natives” (whether of Africa, the Amazon, Micronesia, etc.) are oten drawn with their pelvises covered in what looks like a bush- a low-res depiction of a grass skirt, I presume.
The Andaman Islands are among the most isolated places on earth. These look more like shredded cloth than grass skirts.
Remember these guys? They don’t seem to be wearing much of anything.
There seems to be the concept of a traditional grass skirt from Yap. I don’t know if it is ordinary day wear or ceremonial (or “ceremonial for ceremonies in front of tourists”.)
Coconut Bra appears as early as 1933 in “King Kong.” That’s historical accuracy in my book.
It doesn’t seem like ordinary every day wear, from that link. Most of the pictures of people making them seem dressed in shorts/standard skirts.
I skipped the Yap add-on for the trip I went on. But I have friends who have been there. If no one else pops up with a definitive answer, I’ll try to remember to ask.
Confirmation bias. As in many other places, Hawaiians are very good at showing tourists what the tourists go there to see. Some people assume that anyone dressed in “Western” clothing is not Hawaiian.
Seriously? Okay. Grass skirts are only worn by locals at tourist traps, such as the Polynesian Cultural Center or a touristy luau, where they feature hula or Polynesian dancers. It is not part of everyday attire.
As mentioned before, Hawaiians and other Polynesians have had cloth-making technology for centuries, using fibrous plant tissue that is pounded and dried and painted with plant-based stains. High maka-maka types got to wear capes made out of pretty and now largely extinct birds’ feathers. Images of Hawaiians wearing grass skirts are generally demonstrating the older style of hula; modern hula features musicians and dancers both wearing Western-style clothing.
Casual modern Hawaii attire is a T-shirt accompanied by shorts, with slippers (Mainland folks call the flip-flops). Business casual/dressy mens’ wear consists of slacks and a short-sleeve button-down shirt called an aloha shirt (Mainlanders call them Hawaiian shirts). Mu’umu’us used to be popular with women in the early '80s, but now they wear whatever’s in fashion. Occasionally, you will find a Samoan or Polynesian person wearing a lava-lava, but it’s by no means the norm.
Some sites say the idea of the grass skirt was popularized in Hawaii by workers brought in from the Gilbert Islands in the early 1900s.
Reminds me of a joke from the old Dr Katz animated show on Comedy Central. Some male comedian, I forget his name, says, “I took a trip to Hawaii, and when I got there I was expecting everyone to be wearing grass skirts & coconut bras, but I was the only one…” 