To do this press and hold the Power button until the 'slide topower off' option appears. On this screen again press and hold down the Home button - the screen will flicker and take you back to your home screen. It's as simple as that.
The good news: It also works on other iOS devices like the iPad and iPod Touch.
While it's a good know-how for moments in need, Gizmodo recommends not to overuse the function.