A sharp machete! 5 short, controlled blows slicing the top off till you have what looks like a pencil point. Then the last sharp blow takes the top of the pencil point off so it's big enough for a straw and a spoon. You need to start from a proper whole green coconut - not one with most of its top cut away like that. 🤣 LOL Thai kids learn to do this with a sharp machete when they're about 5. The hammer? LOL. 🤣 When you're done, 1 sharp blow down the middle to split it in two and harvest the meat.