So did you know that the Vikings who gave us "berserk" might have been on drugs? Berserk comes from Old Norse berserkr: ber (bear) + serkr (shirt). Literally "bear-shirt." These warriors were so frenzied in battle they were believed immune to fire and steel. Some historians think the frenzy was self-induced, others suspect hallucinogens. Today "going berserk" just means losing your temper. Last time you went berserk over something embarrassingly small?