Today the practice of sneaking menstrual blood into the food or drink of a man is being taught as if it is a standard and normal practice for female practitioners. In the past this belief was more of an urban legend or fear that men had. It was also a common belief that certain mothers had when they felt their sons had become enthralled with a bad woman. Thus the excuse was that the woman was at fault because she had dosed the son's drink and thus the son was blameless.
Origin: goddesses-and-gods.blogspot.com