See my remarks about a sponge/torus for coffee drinking.
It would take some thinking and working out of the fine details, but I think you would eat the cup as you drank the coffee out of it. You'd have to work quick, before the donut got saturated and started falling apart. Like I said, there are some details that need to be worked out. I'm just the idea man here.
OK, this would be a distinct disadvantage at the Waffle House because you could not refill what you had eaten, but if you were the vendor, it would be great. You would sell the cups and give the coffee away. Really you wouldn't, you'd roll the coffee cost into the cup, but most customers would never catch on. Look at how many people are fooled into thinking that $69.99 is a whole lot less expensive than $70.00
Maybe the donut/cup could have an edible glaze on the outside that would hold it together when it was filled with coffee. A food specialist would know about that, not an idea man.