I had learned, a while ago, by watching this boy's YouTube channel, that one is able to open a can on a cement surface.
Place the can on the cement surface, with the end of the can that has the lid crimped facing down.
Rub the can on the cement block (or other cement surface) in a circular motion for 10 minutes.
At which point the metal crease will be worn through in a few places and, liquid will start to leak from the can, provided, that you are opening a can that has liquid in it. (I did this twice and each time it took exactly 10 minutes)
Use a knife to pry the can open the rest of the way.
You can open a can with a cement block!