People who are claiming to be in the know say that this is a prank, like charging your phone by putting it in the microwave or waterproofing it. This prank will "brick" your iPhone. (Make it unusable).
As cool as this might look, it’s a hoax, and a particularly nasty one at that. Resetting your phone’s date that far back will so thoroughly confuse your phone or tablet’s operating system that you’ll either need to take it to the Apple store for a replacement, or just buy a whole new phone or tablet.
The date bug affects iPhones, iPads and iPod touches with 64-bit processors running iOS 8 or iOS 9. Apple says it’s looking into the bug. Users can protect themselves with a series of tweaks, such as manually setting their time and date, not enabling automatic time changes, and not turning off their iPhone or iPads.