Place the eggs in a saucepan and cover with water. Bring to a boil, then remove from heat and let them sit, covered, for 12 minutes. Drain and cool in cold water.

Peel the eggs and slice them in half lengthwise. Carefully remove the yolks and place them in a bowl. Mash the yolks with a fork, then mix in the mayonnaise, mustard, salt, and pepper until smooth.

Spoon or pipe the yolk mixture back into the egg whites. For a Halloween twist, top with sliced black olives to resemble spider bodies, or add a few drops of red food coloring or hot sauce for a "bloodshot" look.

Arrange the decorated deviled eggs on a platter and chill until ready to serve.