“Ikki-ichiyū一喜一憂” means alternating between joy and sorrow with every small change - being overly emotional about ups and downs. It describes someone who gets too excited or depressed by minor events. EX. 「テストの点数（てんすう）で一喜一憂（いっきいちゆう）するのはやめなさい！」 "Stop getting excited about test scores!"