If you don’t have a can opener, simply grab a spoon. Grasp the head of your sturdy spoon so the handle sticks out past your thumb and a small sliver of the other end can be seen.

Press the edge of the spoon to the outer groove of the can, and while applying pressure, saw the spoon back and forth until it breaks through the can.

From there you should be able to use the spoon to break and pry open the lid until you can access whatever's inside. Just be careful as the can will be sharp.