The Collaborative International Dictionary
goody-goody \good"y-good"y\, n. A person who is weakly, sentimentally, or affectedly good; a goody-goody person; -- sometimes used to refer to person who acts with good intentions but who bunglingly does more harm than good. The latter may sometimes be deprecatingly referred to as a goo-goo. [Colloq.]
Goody \Good"y\, a. Weakly or sentimentally good; affectedly good; -- often in the reduplicated form goody-goody. [Colloq.]
Wiktionary
n. A well-behaved person with no obvious human failings, with the possible exception of smugness and self-satisfaction
WordNet
adj. affectedly or smugly good or self-righteous
n. a person who behaves extremely well in order to please a superior
Usage examples of "goody-goody".
Jessica Darling, textbook goody-goody and Class Brainiac asking him to help me do something very unlike the me everyone thinks I am, myself included.
With the addition of an ape jock called Brad Maxi and a revolting goody-goody brother for Kevin called Aaron, The Suburbs amounted to a wickedly cathartic bloodletting against their shared boyhoods.
Mom and Dad's bedroom is filled to the ceiling with cartons of Goody-goody Bars: Nut Raisin, Cherry Date, Chocolate Banana, and Cinnamon Apple, which is not her favorite.
We break a few rules, and play practical jokes, and we’re not goody-goodies who do everything we’re told.
Try to persuade a couple of the Guild-sisters to come along, too—not goody-goodies like Doria or Keitha, but someone who can travel hard, live rough, chew leather and take orders.
She hated do-gooders, those she called the goody-goodies, but her own goodness surrounded her like a tangible, and visible magnetic field.