squeal (on) v.
1. [mid-19C–1920s] to complain.
2. [mid-19C–1940s] to own up.
3. [mid-19C+] to inform against one’s partners, esp. partners in crime.
4. [late 19C+] to report a crime to the police or any other authority.
[1960s+] (US) the law requiring parental notification when an underage girl applies for a prescription for contraceptives.