Prepare pretzels according to package directions and let cool.
While the pretzels are cooling, stir several drops of red food coloring into the frosting to make it look bright, bloody red. (You might want to spoon some into a bowl to make it more manageable!)
Break pretzels apart into curved pieces that resemble bent fingers. (The extra pieces are for eating!)
If you're using fruit roll-ups, use kitchen scissors to cut them into the shapes of fingernails to fit on the ends of the pretzels.
Use the frosting as glue to attach the fruit roll-up finger nails or half of a pistachio shell to the ends of the fingers.
Spread a little extra frosting around the fingers to make it a gory scene. (Don't forget to put blood on the severed end!)
Spread the crushed graham crackers or chocolate cookies on a serving tray or a baking sheet to resemble dirt.
Assemble the bloody fingers on top of the dirt and garnish with a little more frosting as necessary to achieve a truly awful presentation.