This is not a hack its just a FLY GLITCH!!!
1st:You need to crouch and your friend.
2nd:Move together closer.
4th:One of you should move a little bit backward and move a little bit too to the right.
5th:Then the one who moved a little bit backward and moved a little bit too to the right, should fire a pistol once and then jump together.
Last:You repeat Step 5 until your in the air.
Notes:1st note:Do not move or you'll fall!
2nd note:Don't do it quickly or you'll not gonna go in the air!
3rd note:Do not do it on Zombie Port or you'll die!!!
4th note:And you can do it on any modes!!!
And PRESS Thanks if I helped!!
Enjoy Fly Glitching!!!
And next time i will show you how to go to a wall!!!!