This glitch works in creative mode and you'll recieve an item not accessable in creative mode.
Step 1: Run Minecraft In Creative
You'll need to run Minecraft PE and aquire a bow and bone meal.
Step 2: Shoot and Click
You'll need to shoot the bow and click the bone meal and the same time (this may take time).
Step 3: Ink Sac!
You should recieve the ink sac and it works just like one!
I tested it out on some sheep.