During or before the act of sexual intercourse a woman takes her finger and wipes it across her vagina while she is on her period. She then takes the menustration matter and wipes it across the tongue of her partner(male or female or both at the same time).
Sally: Guess what Rob i got my period today.
Rob: You know what I'm thinking..*looks at Sally*
Sally: *shakes head in agreement*....Rotten Rochester time!!!