The name given to the 'fourth'
Powerpuff Girl, created by
Blossom,
Bubbles, and
Buttercup after they decide they need someone to help fight crime so they might relax and have the day off.
The girls follow the recipe written down by Professor Utonium—adding Sugar, Spice and Everything Nice. Lacking actual sugar and spice, the girls opt for whatever they can find: artificial sweet powder and "dirt and sticks and things." For each of the girls, 'Everything Nice' means something a bit different regarding each of their distinct personalities—i.e.: Bubbles throws in lots of flowers and crayons, Buttercup tosses in a football, Blossom adds a calculator.
After an orgy of Everything Nice ingredients, the girls 'accidentally' add Chemical X, creating a very large, very ugly, misshapen, humpbacked thing which the girls name Bunny before sending her out to fight crime.
Of course, Bunny doesn't really know how to properly fight crime and hilarity ensues.