be a nine days' wonder
US /bi ə naɪn deɪz ˈwʌndər/
UK /bi ə naɪn deɪz ˈwʌndər/
1.
something that causes great interest when it is new, but is soon forgotten
:
•
The new celebrity scandal will be a nine days' wonder; people will forget about it next week.
•
Many new gadgets are a nine days' wonder, quickly replaced by the next big thing.