Some cheats for Grand Theft Auto V are about stuff like makin' money. They justifiably disable the ability for that save to rack up achievements. Others, though, just want you to be free.
This one looks more like something you'd see as a mod for the PC version, but since that inevitability is likely 6-12 months away, this'll have to do.
Warning: you can fly like Superman, but you will die like the rest of us.
Here's how you activate it, via taltigolt:
L1 L2 R1 R2 Left Right Left Right L1 L2 R1 R2 Left Right Left Right
and for xbox
LB LT RB RT Left Right Left Right LB LT RB RT Left Right Left Right