This is a very useful glitch, it allows you to pick up an object multile times, everytime adding to your supply. Performing this glitch enables you to have unlimited, or however many grenades you wish to have.
Anyways, here is the tutorial for this glitch...
1) Get whatever item you want to keep picking up and place it in a corner
2) Get ontop of item so you get the pickup icon and keep pressing LB + X
This video, produced by Exiled Glitchers actually contains more than just the Multi Quck Pickup, if you wish to skip to the Multi Quick Pickup it is located at the 3 minute and 5 seconds mark (3:05).
