Sugar hats, also known as Zuckerhuts or Zucker Huts in German, are small, compact cones of white sugar that are commonly sold in Germany and Austria. Sugar was originally sold here as cones until the creation of sugar cubes. Today the cones are not normally used for cooking but instead are sold more as a novelty item during the Christmas season. They are traditionally used in an alcoholic punch called “feuerzangebowle,” or fire tong punch. This punch consists of heated red wine flavored with cloves, cinnamon, and citrus peel. The sugar hat is suspended over the punch in a special metal plate with holes in the bottom called a fire tong. Rum is poured over the sugar hat and the cone is ignited. The flames make a pretty sight and the heat causes the sugar to melt and drip into the punch.
The sugar hats are difficult to impossible to find outside of Germany. A market that specializes in German food might have one, but an internet supplier is your best bet.
Bodger adds some fascinating info: "I hear that this used to be how all sugar was distributed, and no good Victorian table was complete without the sugar hammer, for smashing hats of sugar.(this seems to be where "one lump or two?" came from. lump was the most precise description.) but that's all referenced elsewhere. I've also heard it asserted that "foo or I will eat my hat" was first popularly used in reference to a hat of sugar - less impossible than consuming a fine beaver, but still an improbable feat unless it was crushed first."