For the Candy Melts - In a small microwave-safe bowl, add the black candy melts. Cover the bowl with a paper towel and heat in the microwave for 40 seconds. Stir the candy melts until they start to soften.
The bowl may be warm enough to continue to melt the candy. After stirring, if they're not completely melted, cover the bowl with a paper towel and warm them just a little bit more in the microwave (about 20 seconds). Be careful not to overheat the candy melts. Stir the melted candy until its smooth.
For the Rim of the Serving Glasses - Turn the serving glass upside down and put the rim of the glass in the melted candy. Twist the glass around until the melted candy covers the area around the rim of the glass.
Then lift the glass from the melted candy. Using a spoon, even out the melted candy around the rim of the glass. Use the spoon to add more melted candy to the glass if needed.
Then quickly, before the melted candy on the rim of the glass sets (dries), add candy sprinkles to it. Repeat the process for the other serving glass/glasses.
After decorating the rim of the serving glasses, an option is to add scary strands or jagged lines around the top of the glasses by using a small spoon to spread some of the remaining candy melts in the bowl (which may need to be slightly melted again in the microwave).
Chill the decorated serving glasses in the refrigerator so that the black candy coating will set (about 25 minutes).While the serving glasses are chilling, make the gummy worm garnish.