http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=782292782
This new trick works 100% after the GTA Online Bikers Update

1) Go to a store and walk up to the counter.
2) Go to outfits > Heist sloppy > And buy the Blue Sloppy Suit. (called Yankton)
3) Buy it and than save it on one of your 10 slots!
4) open up your phone and go to quick job.
5) Do quick heist and join on call. (lobby direct)
6) one the screen shows where you and your heist partners can change outfits. instantly leave.
7) after you return to GTA Online Freemode it should be on your back!
8) Save the suit(outfit) with the duffle bag on your back.

note: IT MAY NOT WORK THE FIRST TIME. TRY IT A FEW TIME IF YOU NEED TO.
note: Make sure to save the yankton sloppy suit BEFORE TRYING THIS GLITCH.

one you saved the dufflebag on the blue suit outfit you can get it on other outfits as well!

First, you have to have acquired the duffel bag and saved it to at least one outfit.
Second, have another outfit saved that is compatible with the duffel bag and have a parchute(ISREAL Skin) equipped on it (showing & Saved).
Now, wear the outfit with the duffel bag
Get into any aircraft and gain a decent altitude
Open the Interaction Menu and go to your saved outfits
Hover over the Saved Outfits option (as it will be grayed out in the aircraft) and jump out
Once the option is selectable, quickly switch to your compatible outfit while freefalling. (May work after chute has been deployed)
Once you've switched, deploy your chute (or splat).
When your character removes the chute, it should be replaced with the duffel bag!

Add me on social club:
http://socialclub.rockstargames.com/member/panda_waifu

I have no friends ;w;

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=542472590&tscn=1456827068