This is a term used by women to describe men that they find unappealing or unattractive, but are too nice to say it outright. It is most commonly used when they are explaining to one of these unappealing men that they do not want to go out with them.
"Would you like to go out with me Agnes?"
"Uh, well, you're sweet, but I don't really see you that way Steve"
This is a natural phenomenom that occurs only in women, because men have no idea what a period is like, women are able to get angry and violent with little provocation and then blame it on their period. All women relish their period, it's the perfect excuse to let out anger with no repercussions at all. The common myth is that they are painful and annoying for women, but in fact it is only men that are adversely affected by periods.
Hannah: "You bastard, I hate you, I'm going to chop off your willy and feed it to some sheep, and they'll knaw it to pieces with they're blunt little teeth, then I'll wee on your face, because I hate you, with your ugly little eyes and your bad teeth (throws vase against wall in anger and begins pulling the wallpaper off the walls) I'm going to kill you, and your family, you sleaze!
Marvin: On your period?
Hannah: Yes actually