This is actually more of a cool kinda thing but you need to activate Parachute cheat and go to Binco's and get a grey/black sweatshirt, g/b shorts and a g/b beanie.

Then once your done go to the tallest building, which is shaped as stacked cylinders.

There's a door somewhere, then when you see that yellow upside down cone go there and have your parachute ready.

Once at the top, go ahead and jump of the edge.

Then when falling move the left analog stick forward, but when getting close to the ground press B to open up the chute.