field day
noun [ C ] uk/ˈfiːld ˌdeɪ/ us/ˈfiːld ˌdeɪ/
US（学生的）体育比赛日，户外运动日
a special day of organized sports or other outside activities for students
Idiom
have a field dayidiom 玩得很高兴；利用机会
to take advantage of an opportunity to do something you enjoy
The newspapers had a field day when the wedding was announced (= they wrote a lot about it and printed many photographs of it). 婚礼的消息宣布后，报纸抓住机会大肆报道了一番。