You could someday need this knowledge. Would you believe that you can open a canning without a can opener ?, There is a way to open those cans [that do not have open-easy] in a simple and fast way, and best of all, you do not need tools, only your hands. This could be very useful, if someday you go out into the field and have been canned and canned to feed yourself but you forgot or lost the can opener; so this will be very useful for you. Pay close attention, a couple of crazy Russians, has a YouTube channel where they teach us this great trick that could be very useful here we leave it. Please share with those that you think may be useful.