- (often repeated, childish) Imitation of the sound of a baby who hasn't yet learned to speak.
- 1998, Ramtha, The Children's View of Destiny and Purpose 
- And the parents go, "Goo-goo, ga-ga, goo-goo, ga-ga."
- 2001, Jessica Teich, Brandel France de Bravo, Trees Make the Best Mobiles 
- If goo-goo, ga-ga is as foreign to you as a radio broadcast from Ouagadougou, try this definition of “baby talk”: It’s talk directed to your baby, concerning her care.
- 2002, Griff L Ruby, The Resurrection of the Roman Catholic Church 
- Their attempts to return to the primitive Church structure have invariably been every bit as inauthentic as an older child’s attempt to imitate a baby by shaking a rattle and shouting “goo goo ga ga!”
- 2004, Jack Canfield et al., Chicken Soup for the Unsinkable Soul 
- I get Denise’s bag while she, my wife and ex-wife all make goo-goo ga-ga noises over Denise’s half-sister, now almost two years old.
- 2005, Mort Walker, Conversations, Jason Whiton ed. 
- But I had read something by Sinclair Lewis many years ago, and there was one page where some guy was looking down in the baby carriage going ‘Goo goo ga ga’ and the baby was thinking adult thoughts like ‘Ah, the stupid guy. What’s the matter, can’t he talk straight?’
- 1998, Ramtha, The Children's View of Destiny and Purpose