The time of the month in which a man bitches about everything and acts like a big pussy usually caused by a women's lack of sexual drive and bad attitude during her menstrual period.
Yo Bill is totally on his manperiod he has been pissed and acting all sick this week, it's probably because Becky got hers too.
A man-period is the time of the month where a man will get angry and horny for no real explanation. During the time frame of 4-7 days a man will be more likely then not to A) Punch some fucktard in the face B) Sleep with Random women C) Yell for no real reason or D) Rip clothes off of spouse/girlfriend/significant other. During this time it is advised to appease the man with porn, sex, or junk food.
Man suffering from Manperiod -*Looks around* "Grrrr mumble grumble...."
Random guy - "What are you looking at?"
Man - "SMASH!" *Rips head off of stranger and shits down neck*