To thrust the penis between a women's preferably large breasts and ejaculate on her chest and/or face. can be used as a noun or a verb. (explanation for the sex-impaired: breasts contain milk, and you bone them, hence the term "milkbone")
Hey Angi, i would really like to give that large breasted lady a milkbone.
Tom really enjoys milkboning his wife, who i am told has relatively large breasts.