Green’s Dictionary of Slang

1. sweet, sickly .

1903		E.W. Townsend Sure 107: Some goo-goo stuff dat Duchess calls patty.
1906		S. Ford Shorty McCabe 141: She tips me a goo-goo smile that was all to the candied violets.
2010		(con. 1973) C. Stella Johnny Porno 263: The jerk she was all goo-goo over, yeah.

2. (US) effeminate.

1963

in T.I. Rubin Sweet Daddy 118: Sometimes they [i.e. ‘gay boys’] make with the real goo-goo stuff [i.e. clothes]. You know so you can see them a mile away.