New York Penal Law section 230.00 defines prostitution as "A person is guilty of prostitution when such person engages or agrees or offers to engage in sexual conduct with another person in return for a fee." People v. Costello, 90 Misc .2d 431 (N.Y. Sup. Ct. 1977) defined sexual conduct as including "sexual intercourse, deviate sexual intercourse, and masturbation." I can't find a New York citation offhand, but legally, masturbation traditionally means hand manipulation of the penis, whether by its owner or by another person. New York courts have broadly interpreted the definition of sexual conduct. For example, in  People v Hinzmann, 177 Misc 2d 531 (Crim Ct, Bronx County 1998), lapdancing, specifically "to pay someone to sit on a lap and gyrate, while having their naked breasts and buttocks fondled," constituted acts of prostitution.