The best way is to find a bamboo stalk about 3 inches in diameter. It goes without saying that you have to chop it off the tree, when that's done carefully cut off one end at an angle to it's length. It should look like a primitive hunting spear when youre done (see photograph above). Position your bamboo spear on a rock or platform about a foot off the ground, position a container with a wide mouth beneath it and then start scraping the meat off the shell. When youre done, add some water to the grated coconut meat, then you should be able to squeeze about a glass of coconut milk from this.
You can add your coconut milk to a few pieces of freshwater shrimp, snails, or if youre a little hard up on ingredients, maybe just a few vegetables that you've managed to scrounge! Enjoy!