When a woman's time of the month makes her extremely grumpy/angry/hungry. Inspired by "Modern Family".
Luke: Did you see Alex cry about the commercial, then scream at me for not bringing her enough ice cream?
Phil: Yea she's totally monsterating right now, stay away.
When two or more women in a household are synchronized with their menstrual cycles.
I have to get out of the house this weekend. My wife and daughter are monsterating.