turn into a pumpkin

From the story of Cinderella, in which the transformed coach reverts to its original state (that of a pumpkin) at midnight.

turn into a pumpkin

1. (idiomatic, colloquial) To go to bed; to go to sleep (especially at, or around midnight).

   I'm about ready to turn into a pumpkin. You can stay up later if you want.

   Tell her I'm turning into a pumpkin if she stays out too late. She won't be getting a lift from me.

2. (idiomatic, colloquial) Used to indicate a curfew, or the time by which one must depart.

   My daughter turns into a pumpkin at 10:00, so you need to have her home before then.

   I'm turning into a pumpkin at 4:00, so we need to finish this.

   "I need to get back now!" "Why? Are you going to turn into a pumpkin?"