A friend who has Xbox Live and the game is required. Have him create a lobby and join it, then leave to go to your wardrobe. Remove all the upper body clothing (not including hats), then go to the store and buy an expensive item (platinum chain or other jewelry). You will be told that it costs too much, but your character model will be wearing it to show you what it looks like. While wearing the chain or other accessory, open up your friends list and join his game. You will be wearing the chain when in the lobby. Repeat this process until you get everything desired.
Skip the online lobby and go directly to the customization tab on the Xbox Live section. Choose "Body" and, as soon as the screen loads, press Y to quit and make sure to save with A. Then, scroll down to purchase clothing and select it. When it loads, find the item of clothing desired. When you see the clothing on your character's body, join a friend's game in progress or have someone send you an invite. Join their game. Note: The glitched clothing cannot be removed unless you buy a piece of clothing of the same type, such as coat or shoes, and wear that purchased piece of clothing.