In other words,item duplication,its also the best way to get gold faster.First of all you need two gamertags and controllers.You can just create a temporary profile just to control Sheva with P2.Item duplication does not work with weapons and aid spray.So start at any chapter,preferably in chapter 3-1 since they hv jewels nearby.Clear your backpack beforehand and just put in any items you want to duplicate such as Ammunition,grenades and eggs(white,brown,golden egg for 1000g or rotten egg which costs for 2000gold)Skip cutscenes by pressing 'back' button,and press start on P2 controller to sign in as Sheva.And when you're ready,transfer the items from Chris to Sheva.Quit and Overwrite both profile.Get back in again,but this time control Sheva and give back the item to chris.Quit and only overwrite chris's profile.Get back in,you should clearly get duplicated items,repeat the process.I sold 45 golden eggs and got 90000g each time XD,but i got no luck in getting rotten egg.So its also the best way to upgrade your weapons.I found this cheat by myself,but i just realize it has been posted in the web for a long time ago XD.Anw happy duplicating!