1
general::
Phrase(s): go berserk
to go crazy. • She went berserk and strangled her cat.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Erupt in furious rage, become crazily violent. For example, When they announced the gymnast's score, her coach went berserk. This expression is believed to allude to the name of Norse warriors renowned for their ferocity in battle and for wearing no armor but a bearskin shirt (or berserkar). [Late 1800s] Also see GO APE.
American Heritage Idioms