Behold, the edible coffee cup:

The baked cup is lined with a special icing sugar that makes the cup waterproof (for enough time to drink the espresso anyways) and sweetens the coffee at the same time. 

Michael Coren examines other types of edible packaging:

Containers to chow down on are becoming a bit of a trend. French design company Miit came up with a recipe for a digestible version of a chocolate fondue pot, while a Harvard professor has developed biodegradable plastic membranes that taste like their contents and may be eaten along with them. Bon appetit.

Update from a reader:

Not a new idea.  You no doubt know the source of the term/disease "trench mouth":