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To suddenly and unexpectedly act in a viscious manner; esp. in regards to a woman.

Historical Usage: from a comment made concerning a Detroit woman who sued a charity because its name infringed on her charity's name.
"Yeah, I would have said she was a nice person... if she hadn't psychobitched out at the party last night!"
by Brandon Hendrickson March 14, 2003
go haywire esp. a woman
by Moonshot March 14, 2003