These are betel nuts. Everyone in Papua New Guinea chews them (mixed with lime (like from limestone) and mustard incessantly and spits out the blood red juice.
This is what it looked like when they got Ryan and I to try them. I don't think we'll be taking it up any time soon:
A bit more fun: Me taking blood out of the back of the 4 x 4.
And this deeply charming bit: An old woman who adopted Ryan as her son, and in the tradition of mother-in-laws to their daughters, gave me a bilum (the string bag). SO MANY BILUMS (seriously, I have like eight now.)
Here's the women making the bilums. They are constantly busy with them, which may explain why they feel they can give them away, even in a society full of people with so little.
All in all, it was an amazing trip. We would highly recommend PNG to any bold/independent travelers, especially those looking to meet charming local people while visiting beautiful mountains. Spend as much time as you can in the remote areas and you'll have a wonderful time.