The classic fish and chips with russian dressing requires at least three people, one of which must be a woman on her period, and one of which must be a man. The man penetrates the bleeding woman (this would be the fish and chips) and upon orgasm completes the preparation of the russian dressing, i.e. semen mixed with menstrual blood. The third person simply laps everything up from below. While the gender of the third person is irrelevant, their presence is necessary because it's only an FnC with RD if someone is eating it.
Man: I heard Napoleon was all about the fish and chips with russian dressing.
Woman: Oh word?