Why Risk It?
Why risk doing damage to your axe? Slides come in a wide variety of materals, thicknesses, weights and colors as well as being a lot easier to use than a bottle. Granted it may look cool to just grab a bottle and go, and if you've had plenty of experience with slide it may work. If you use the same guitar for slide and regular playing you will also get a very sticky guitar if you spill beer (or anything else except WD40, maybe) on it. also you will risk shorting something or at least getting beer in one or more of your pots and that will make a guitar sound like crap. If you have a rosewood fingerboard you should never deliberately put anything other than a little lemon oil on it. One last thing, it took me more than twenty years of playing to realize that alcohol and guitars do not mix, both the internal and external kinds.