a labelling question

[ratcreature]

Do you consider stories or art in which a character masturbates without it being clear what/who the object of their fantasy is gen? I don't see this happening very often in stories, but I've been tagging art for the LJ fanart listing for a while now, and try to tag art as gen, het, slash and/or femslash, but I never quite know what to do with (solitary) masturbation pictures.