Dragon Fruits are rare and they bring +50 if you get it. It will appear randomly so keep an eye on it. For the special fruit secret, you play classic mode and eventually a big fruit will fly across the screen from left to right. Not only will you get the achievement but you will also get 50 bonus points. For the secret ones, you have to get 0 fruit, 69 fruit, 99 fruit, and you have to get your exact high score, then you just let youself lose. This is the way to unlock Year of the Dragon Fruit Ninja Achievement.