A comic variant on the more trite YMMV (your mileage may vary), used as a caveat indicating that an assertion is believed to be true, but may vary in degree for different cases. YPMV references those who believe that eating the placenta after child birth will give nutrients to stave off post partum depression, increase milk supply with several unspecified nutritional benefits to the mother.
YPMV is rumored to have come from a South Park writer's idea on the topic of Tom Cruise's child's birth and Scientology practice, but the line apparently never made it in to the target episode.
Some mothers report tremendous benefits from the seemingly bizarre practice of eating placenta after childbirth, while other study subjects report no benefits at all. Apparently, YPMV!