"You'll tidy your room?" "That'll be the day."
that'll be the day
idiomSaid in reply to something that one believes will never happen.
Origin
disputed originOriginally referring to a significant day in the future regarded as worth waiting for.
When my brother said he would stop playing video games, I laughed and said, "That'll be the day."
She promised to arrive on time for once, and her skeptical colleague muttered under her breath, "That'll be the day."
- 01
a cold day in July
The time of occurrence of an event that will never happen.
- 02
a day late and a dollar short
Too late and too feeble to achieve the desired effect.
- 03
a year and a day
A long time.
- 04
as the day is long
Unceasingly; very; thoroughly; to a very high degree.
- 05
bad hair day
A day when things seem to be unmanageable or go wrong.
- 06
banyan day
In British naval tradition, a day of the week when galley kitchens served no meat on board ship.
- 07
black day
A day of great disaster, misfortune or unhappiness.
- 08
call it a day
To cease an activity.