A term used to refer to the fact that a female is currently menstruating.
person a: "Hey, do you wanna go shopping later?"
person b: "Ugh, I wish I could... the bitch is back. I have a date with my heating pad."
male person a: "So are we gonna have sex tonight?"
female person b: "The bitch is back. What do you think?"
male person a: "...beej?"