“As a rule, menstruation is generally not something seen in porn, which is a peculiar omission in an industry that fetishizes everything from shoes to stuffed animals to excretory functions. Though credit-card processing companies seem to have no problem with double- and triple-penetration sites, bukkake, and electricity play, most of them regard menstruation and other forms of blood play as out of bounds, citing obscenity violations as well as safer sex concerns---though anal cream pies and the like are at least as risky.”