Place chicken thighs in a lightly greased 9x13 inch baking dish. Season with salt and pepper to taste and bake in the preheated oven for about 25 minutes.
Meanwhile, in a medium bowl combine the oyster sauce, garlic, sugar and water. Mix together and taste the sauce; if it is not sweet enough, add sugar to taste.
After chicken has baked for 25 minutes, pour sauce over it and bake for another 20 minutes, or until chicken is cooked through and juices run clear.
