have a field day
US /hæv ə fiːld deɪ/
UK /hæv ə fiːld deɪ/
1.
to have an opportunity to do something enjoyable or to exploit a situation to one's advantage, often with negative connotations for others
:
•
The tabloids will have a field day with this scandal.
•
When the teacher left the room, the students had a field day.