A sexual act in which blue
slurpee,
soft drink or food dye is placed into a menstruating vagina. The subsequent period blood which comes forth, along with the
blue drink is known as the blue moon, due to the blue colour and the period happening once a month, or moon.
Steve:
Shana told me she was on her period last night, so I decided to give her a blue
moon.
Jay: Cool
digs man.