Preheat your oven to 375°F (190°C). Line a large baking sheet with parchment paper and set aside.

Open the crescent roll dough and unroll it onto a clean surface. Using a sharp knife or pizza cutter, cut the dough into long, thin strips roughly 1/2 inch wide. You don't need to follow the perforations — just cut straight across the whole sheet of dough.

Pat the hot dogs dry with a paper towel. Starting at one end of each hot dog, wind a strip of crescent dough diagonally around the dog, overlapping slightly as you go. Leave a small gap about one-third of the way down from the top — this is where the face will go. Press the ends of the dough strips firmly to seal. Repeat with all 8 hot dogs.

In a small bowl, whisk together the beaten egg and water. Using a pastry brush, lightly brush the crescent dough wrapping on each mummy with the egg wash. This gives the pastry that deep golden color and glossy finish.

Arrange the wrapped hot dogs on the prepared baking sheet, spaced about 1 inch apart. Bake for 12–14 minutes, or until the crescent dough is deep golden brown and puffed. Start checking at 12 minutes — oven temperatures vary.

Remove from the oven and let cool for 2 minutes. Transfer the yellow mustard to a small squeeze bottle or a zip-lock bag with a tiny corner snipped off. Pipe two small dots of mustard onto the exposed 'face' area of each mummy to create the eyes.

Serve immediately on a platter with ketchup, mustard, or your favorite dipping sauce on the side. Watch them disappear.