In an early chapter, you'll meet a girl who asks you to scrounge along the beach for water and food. She'll next ask for canned food. Once you retrieve around 10 or 20 cans, toss it on the ground and then kill yourself. As the recover process follows, quickly load your last checkpoint and access your inventory. Scroll down and you should find that the cans are back in your inventory. They also should be on the ground where you left them before loading your checkpoint save. You can keep repeating the process to mass a huge pile of cans that you can use to gain experience and money.