Preheat oven to 375℉. Unwrap crescent dough and lay flat on a cutting board. Cut at the perforations to create 4 even rectangles. Press the other perforations to seal.
With a sharp knife, cut each rectangle lengthwise into 10 strips, making a total of 40 strips of dough.
Take one hot dog at a time and make two slits along the sides for the mummy’s arms. Make a slit at the bottom for its legs.
Wrap strips of dough around the individual arms and legs, then around the body of each hot dog, leaving small space for where the mummy’s face will be.
Place mummies on a large (ungreased) sheet pan and lightly spray the dough with cooking spray.
Bake 12–15 minutes or until the dough is light golden brown. Pour some mustard in a plastic bag and snip off the tip of the bag with scissors. Pipe “eyes” on the mummies.
Enjoy mummy dogs with extra mustard and ketchup if desired.