The means by which a group of cohabitating women (such as a sorority house or college dorm) wirelessly synchronize their menstrual cycles such that by the end of a school year every woman in the house has her period simultaneously.
"Wow, I mean, like, its like totally a cruel coincidence that we all have our periods before the big mixer this weekend! I was looking forward to whoring it up!"
"I know right? But its no coincidence, our whole house is a Vagfi hotspot.