Green’s Dictionary of Slang

(US) statutory rape.

1975		T. Berger Sneaky People (1980) 141: Baby-rape will land you in the hoosegow.
1999		D. Carbado Black Men on Race, Gender [etc.] 316: How confused and tortured he [i.e. Eldridge Cleaver] must be to equate homosexuality, baby-rape, and the desire to become the head of General Motors.