An angry period monster, or APM, often exhibits the following characteristics, including, not but limited to, violent mood swings, irrational behavior, frequent irritating text message sending, being annoying, ruining your day, destroying your concentration before a test, and just being an overall bitch.
Also called angry menstruating monsters, or AMM's (pronounced "AY-DOUBLE M").
A typical text message conversation between a male and an angry period monster:
(9:43 AM) APM: can't wait to see you this fridayy!
(9:45 AM) Guy: yeah, can't wait
(9:46 AM) APM: you know what, fuck you. you're a fucking asshole.
(9:48 AM) APM: wtf is your problem asshole??
(9:51 AM) APM: you know what? im just done. bye.
(9:54 AM) APM: are you fucking kidding me? what the fuck is your problem?