A monthly three to five day period when a man seems particularly moody, weak, emotional or indecisive.
Dude 1: "Hey, have you talked to Jeremy lately? He started to cry when I told him he had a flat."
Dude 2: "Oh, leave Jeremy alone. He's manstruating. He'll be better in a couple of days."
Dude 2: "Oh, leave Jeremy alone. He's manstruating. He'll be better in a couple of days."
by Robert the Great February 05, 2013
by Robert the great June 06, 2007