Green’s Dictionary of Slang

(US) pertaining to prostitution, thus prostie beef, a charge of prostitution.

1930		R. Whitfield Green Ice (1988) 69: Hop up and if it’s a prosty joint we’ll get a funny box on it.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 35: Four prosty beefs/one hot-check caper/one dope bounce.
2021		J. Ellroy Widespread Panic 21: ‘Prosty beefs galore’.