No problem. Now, stick with me here b/c I have some examples...but it all works into a design thought.
This is the only Grumpy specific cake I've seen produced by the Disney bakeries...
I like Grumpy's expression on here, but the rest of the cake is a pretty average design. Now, I don't know what your budget is, but I'd love to see an edible image of Grumpy like this one combined with the glowing jewel chest/car like on the cake below. Obviously, this cake is all the dwarfs, but I'm sure they could make Grumpy larger just to balance things out more.
Since this would be a Grumpy specific cake...I think you can use the concept incorporated into the Cinderella cake below...
Obviously, it wouldn't be decorated in draping, but I think it would look really neat to have the same concept done with some of Grumpy's more iconic moments in the movie.
Ex. When they force him into the bath, when Snow White kisses him on the head, during the Silly Song, etc.
While the execution isn't great in my example below...they could even string the edible images of Grumpy together to make it all look like movie reel clippings.
Ok...final thought with it...while the cake below is about as far from a Grumpy cake as you can get...the edible scrolled message on the front is a concept you could work into the front of your Grumpy cake. If you were to top said cake with an edible 2D stand up Grumpy and have the glowing jewel chest...you could have a message on the scroll like "Grumpy, but a Real Gem." OK- just an example, but a nice little witty way to tie in the wording to the cake with a scrolled msg like the one below.
I hope it makes sense...if I had a little more time I could make a rough sketch of my idea, but I think this is my official downtime of the evening. At the very least, you might be able to work from this and get some ideas. Hope this helps.