Ok, that sounds dramatic. But if you want the ultimate shortcut to your favorite iphone action (turn on camera, take a screenshot, put on your flashligh) here's what you do:
Settings,
Accessibility,
“Back Tap.”
Then you can choose from a bunch of options what the 'secret button can do'.
Once you set it, the secret button will be ready to go (on the back of your phone right below the iphone logo.