Place the eggs in a pot and cover with water. Bring to a boil, then reduce heat and simmer for 10 minutes. Drain the water and cool the eggs under cold running water.
Peel the eggs and slice each one in half lengthwise. Gently remove the yolks and place them in a bowl.
Mash the yolks with a fork. Add the avocado, mustard, salt, and black pepper. Mix until smooth and creamy.
Spoon the filling back into the egg white halves, mounding it slightly.
Add two olive halves to each filled egg for eyes. Place one red bell pepper strip below the eyes to form a mouth.