when a woman gets on her period but unlike regular times this time she goes apeshit.
Girl: My stomach hurts buy me some crackers.
Guy: Its midnight thats ridiculous we don't even have crackers.
Girl: (slap) I don't care get me some god damn crackers!
Guy: WTF you such a period banshee!
When you have a random hatred for someone then find out your periods are out of sink! this could be natural or just a reason to hate someone!
The periods must be out of sink for at least 5 days to be an official periodism
when you really hate someone then find out that you have out of sinkperiods! periodism!