If you dial the number 1-999-367-3767 into your phone in GTA 5 Story Mode, it will show up as calling the name ‘Black Cellphones’, then something very strange happens as you’ll see in the video above.

Not only will your phone will grow slightly in size, but it will also change colour to black and grey. And if you look up a small explosion will trigger.

The explosion is barely enough to do any damage, but if other characters or pedestrians are nearby then they will react to it to take cover briefly.

It’s difficult to know if this is an Easter egg, a mystery to unravel, a glitch or just some unfinished code. GTA being GTA numerous conspiracy theories have emerged.

The most likely explanation is that this is code that was written for a mission that was never released or at least has yet to be released and that calling ‘Black Cellphones’ was part of the mission requirement. One theory is that the numbers can be interpreted as 1-999-EMP-DROP (electromagnetic pulse), but that still doesn’t explain the purpose of including them in the game.

Or maybe it’s just Rockstar trolling the GTA community…