Place hard-boiled eggs in a bowl and add a few capfuls of white vinegar. Roll the eggs around so they are completely covered by the vinegar.
Put the eggs in a colander, add a few drops of food coloring. Roll the eggs around gently. Wait a minute to let the food coloring set.
Add more food coloring. Roll eggs around and wait another minute.
You can add another color if you'd like. Let the eggs fully dry, preferably overnight.
Or, you can rinse the eggs after you finishing coloring them for a brighter look. These eggs will not require a night to dry.
Easter egg dye kits will only run you about $5 but this is perfect in case you're too busy to run to the store. There are also fun to make any time of year.