First you need to buy a soda can equal in size to your beer can, so that you can use it as a cover.
Open the can and pour soda out in a glass or a jug or just ask a friend to finish it off for you. Once the soda can is empty, you need to grab a cutter and remove the entire top of the soda can. Do this carefully to make clean cuts and watch out for the sharp edges.
Now you need to repeat the same on the bottom of the can and remove it completely.
You now have to open the can completely, for which it is important that you find a straight line on the side of the can which you can follow as you cut it open. Begin from the bottom and move your way to the top of the can. Once finished, you will be able to open the can.
It is recommended that you use a metal file to smooth the edges of the can so they don't cut you when you hold it.
You now have to restore the shape of the can for which you need to roll it up. Hold it in its position with the help of your hands and then gently let it go. The can will retain some curve which will be enough to hold its position when you slide it on the beer can.
Now grab the beer can and before opening it, you need to slip the soda can cover over it. Remember, only the top of the beer can should be exposed while the rest should be covered by the soda can.
Once the can is in place you can enjoy your beer in peace.