PNG POM Life says
When you are in PNG you will often find a red-colour stain on the ground, or on the road and wonder what it is… The answer is Betelnut – also known in PNG as Buai.
Buai is not food, but locals love to chew it with mustard seed and dipped in lime powder (which is made from crushed up shell). This combination creates a chemical reaction that turns the mixture bright red, gives the chewer a relaxed feeling, and also reduces their appetite.
Many elderly Papua New Guineans who have chewed their whole life, have red stained teeth and are often missing numerous teeth!
Buai is not illegal because it was traditionally chewed by village elders during meetings with neighbouring village elders.
The red mixture stain on the road is usually spat out after chewing.
This is quite unhygienic, and contributes to the high levels of TB across PNG!
If you are in PNG you can try Buai, but as it may cause problems to your mouth and teeth due to its high acidity – it would be better to try it just once to experience it.
Many PNG people love chewing Buai daily, just like we enjoy drinking a cup of coffee.