The phrase 'Field Day' is used to describe a circumstance in which excitement and fun prevails.
Example of Use: “The boys had quite a field day at the water park.”
The origin of the term 'field day' comes from the military and refers to maneuvers that took place in a field, but by the 1800s, the phrase was used to refer to any event that happened in a field, ranging from a hunt to a dance to a picnic to a scientific expedition.