Step 1: Go to Settings
Step 2: Go to General
Step 3: Go to Accessibility
Step 4: Turn Grayscale On
Step 5: Make a Folder
Drag one app on top of another to create a folder.
Step 6: Drag Apps in the Folder
Step 7: Go to Another Page
Drag the folder to the right.
Step 8: Get All Apps in the Folder
Repeat steps 6 and 7 until all apps are in the folder. Press the home button twice to go back to the first page, which will now be blank.
Step 9: The Result
Step 10: Reversing the Prank
If you are the victim of this prank, go to settings by finding and tapping the icon in the folder, then go to General > Accessibility and tap the Grayscale switch to turn it off. Then, go back to General, tap Reset, tap Reset Home Screen Layout, and then tap Reset Home Screen on the confirmation alert.