Beer is one of those beverages that feels ultra-modern, but has actually been around for millennia, with ancient Babylonians, Mesopotamians, and Syrians all leaving behind ample evidence of their brewing. So you would think with thousands of years of history, someone would come up with a fool-proof way to store an opened in the fridge. While there are no superlative methods for preserving an opened beer so that it tastes just like it did when the seal was first broken (though there is a ), you can get close, and with some methods, stretch your beer to about three days in the fridge.
One of the easiest and cheapest methods is to take two pieces of plastic wrap and secure them around the mouth of the bottle or the top of the can with rubber bands. Then place the bottle in the fridge near the back and bottom (where it's coldest) to help reduce oxidation and loss of carbonation and to keep its exposure to sunlight to a minimum. This technique actually keeps beer fairly well for a few days.
Some more reliable methods for storing an opened beer in the fridge There are other methods, of course, for keeping your beer fizzy and flavorful in the fridge for a few days, but they do require the use of some tools you might not have readily available (but can certainly order ahead of the next time you crack open a cold one). If you save your wine corks or have them on hand for decorating purposes, try pushing one into the mouth of your opened beer bottle to preserve the liquid inside for a .