The Crazy Russian Hacker guy is at it again with this brilliant survival tip that shows you how to open a can without a can opener.
His technique is simple. Find a flat concrete or brick surface, turn the can upside down, press hard and run the can against to surface. This basically files away the rolled lip edge of the can, which then allows the can to pop open by gently squeezing the can.
The lip does not have to be completely filed away. It just needs to be filed to the point where the thickness of the metal is worn through. At this point, the can is no longer sealed.
For food items be sure to brush away any metal filings before the can is popped open. One other point. The Crazy Russian Hacker dude uses cat food as an example. Cat food most often uses aluminum cans, which is much easier to grind away. It will take more work to do this with a steel can.
We did try it on a concrete driveway and it works. Older concrete with a rougher surface will open cans faster than new concrete, which may be much smoother and less abrasive.