Field day
WordNet
noun
(1) A day devoted to an outdoor social gathering
(2) A time of unusual pleasure and success
(3) A day for outdoor athletic competition
(4) (military) a day for military exercises and display
WiktionaryText
Etymology
Apparently the idiom is derived from the military use. A parade is much easier than the soldiers’ usual drilling and forced exercise.
Noun
- A parade day.
- A school day for athletic events; a sports day.
- A day of class taken away from school for a field trip.
- A great time or a great deal to do.
- They went to the park and had a field day playing on the swings.
- A great time or a great deal to do, at somebody else's expense.
- The reporters will have a field day with a comment like that.
- The scandal was a field day for the press.
- Top-to-bottom all-hands cleaning.