If using crescent rolls: Unroll dough; separate into 4 rectangles. Press perforations to seal. If using dough sheet: Unroll dough; cut into 4 rectangles.
With knife or kitchen scissors, cut each dough rectangle lengthwise into 10 pieces, making a total of 40 strips.
Wrap 4 pieces of dough around each hot dog to look like "bandages," stretching dough slightly to completely cover hot dog. About 1/2 inch from one end of each hot dog, separate "bandages" so hot dog shows through for "face."
In 2-quart heavy saucepan, heat oil over medium heat to 350°F. Fry mummy dogs in hot oil, 2 at a time, 1 1/2 minutes, turning occasionally or until dough is completely cooked through and deep golden brown. Drain on paper towels.
Use ketchup to make "blood" on mummy dogs. Serve with additional ketchup and mustard.