In an 8- to 10-inch frying pan over medium-high heat, cook bacon, turning slices as needed, until browned on both sides and crisp. Transfer to paper towels to drain. When cool enough to handle, crumble bacon.
Cut each egg in half lengthwise; gently scoop out yolks and place in a bowl. Mash yolks with a fork, then stir in mayonnaise, green onions, mustard, and crumbled bacon until well blended. Add salt and pepper to taste.
Spoon or pipe about 1 tablespoon yolk mixture into the hollow of each egg-white half. Serve immediately or cover and chill up to 4 hours.