How to open a can without using a can opener or any tools. Great survival tip if you have canned food and don't have any tools or a can opener. All you need is a little water a concrete, asphalt or rock like surface and some elbow grease. It takes approximately a minute to get the can open. I guess you could bash it open with a rock, but it would make a mess of what ever is in that can you want to get into.