Pull top cans.
I take a knife and punch a hole in the can. I then insert the knife into the opening and work my way aroung.JUst be careful and hold the can tightly
taking a knife,a short handled one put the blade colse to the edge and hit it in then cut the can with the sharp blade moving around the edge it will work just like a can opener.Be careful not to let it slip as to cut yourself.
Since anything which can be used to open a can technically becomes a can opener...no, not really.
Interesting method to resort to.
Use the ring pull on the can