Cut gently, severing the hairy, leathery skin without piercing the flesh. Carve halfway around the fruit to extend this slit. You can tear the skin with your thumbnail instead, or even bite open a slit. The cut skin should tear apart easily. Pull one side completely off the fruit, as though opening a hinged lid. Squeeze the remaining skin gently to pop the edible flesh into your hand.
The seed in the center is not edible while raw. Cut into the flesh without severing the seed, and try to pull it out. Some rambutans have seeds that slide out easily, while others stick to the flesh. If you have a clingstone rambutan, just leave the seed in and spit it out when finished.