This will crash your game so beware
Step 1: Open Minecraft and select single player
Step 2: Go to More World Options and change World Type from Default to Superflat
Step 3: Press Customize, Then Presets
Step 4: Click the box at the top and delete ALL the text
Step 5: Copy and paste the Preset into the box then press Use Preset
Step 6: Press Done then Create New World
Step 7: Enjoy Crashing Your Game