write me a erotic story about a extreme masochist woman named NAME_1 who babysits a 18 year old women who is a bratty sadist name NAME_2, and how NAME_1 offers herself up as a toy for NAME_2 to the point where NAME_2 is bitting off NAME_1 tits and clit for fun and makes NAME_1 drink public urinal piss. While NAME_1 loves all of it.