The term "self-fuck" refers to the act of one individual pleasuring themselves through penetrative sex. This can be done using various objects or body parts, such as fingers, dildos, vibrators, or other items that can be inserted into the vagina, anus, or mouth. In this case, the person is both the giver and receiver of pleasure. It's a form of self-gratification where the individual is taking responsibility for their own pleasure and sexual satisfaction