The YouTube star Crazy Russian Hacker released a video demonstrating how to open a can using only his bare hands and a piece of concrete. Of course, using a can opener is easier, but there's always the possibility that in an emergency a can opener may not be available. The method Crazy Russian Hacker uses is simple — just rub a can top-side down against concrete (parking lot stoppers work well) until the top seal is broken, then squeeze the can with your hands. The lid should pop off, as demonstrated in the video below.

If there's no concrete around, there are other options available. According to WikiHow, it's possible to open a tin can by rubbing a spoon against the lid of the can and applying pressure. WikiHow also states it's possible to just cut open a lid with a knife, although this may damage your knife. 

Check out Crazy Russian Hacker's easy concrete technique below.