The spectator is encouraged to inspect a Large Green Beer bottle to make sure that it is solid. It can be bashed with a solid piece of wood showing or banged on a hard wooden surface to show it to be virtually indestructible. You take the bottle back and concentrate on it and with an explosion reminiscent of a rifle shot and exactly on your command the bottle shatters completely. There are also hundreds of other variations on the handling, for example you can just apparently blow into the bottle and it shatters.
Bologna Bottles, sometimes known as The Devil's Beer Bottles, have been around for decades and are often seen in science experiments, the bottles are a genuine Beer bottles and are totally examinable. They are made by heating the bottle to extreme temperatures and then rapidly cooling the inside, whilst slowly cooling the outside. This puts incredible tension on the glass on the inside of the bottle and even though you can hit it hard on a wooden surface, it won't break. To break it, you drop something small and brittle in it, something like a small piece of broken glass, or ceramic or you get a small piece of metal with it that you can also use. You can either hold the brittle object in your hand and as you hold the top of the bottle, just secretly drop it inside and wait or you can have something inside already (drop it in carefully) and just shake it and wait and it will just shatter on it's own..