.
.
Just remove the bottom of a can, slit the side, slide it on top of your opened beer, and tape-up the side. [You can cover most of the bottom too by slitting opposite sides of the removed can-bottom and then shoving it onto the bottom of the beer can.]
If you partially-remove the lid with a can opener, it's easier to drink the beer.
Alternatively, you can just remove the top and bottom, slit the side, and tape it back up into a cylinder again.
