When a woman performs a sexual act and after (or during) said act calculates the relative worth of act. Often, this is followed by demands for remuneration from the recipient of act.
Damn, Tiffany gave me the hottest blowjob last night... then she ruined it by doing whoremath and making me take her out to dinner afterward instead of just going to sleep.
A girl closely related to or one and the same as a "Cum Guzzling Gutter Slut" So ready for sex that she has a mattress strapped to her back at all times.
Rob's nickname for his girlfriend was either "Mattress Back Whore" or "Cum Guzzling Gutter Slut" though he rarely called her those names in public.