"A Bandwurmglas (literally, a “tape worm glass”) was used for drinking games, wherein the spiral band wrapped around the cylindrical, tapering body would mark positions, from which to which the participants would be required to drink: failing to do so would mean that they had to try again and drink on until the next mark. As participants got more and more intoxicated, the better it was that the spiral wrapped around the glass’s body gave them a firm grip. Yet most of these glasses have been damaged and destroyed, making the surviving examples especially rare." The quoted information is from Minneapolis Institute of Art.