It's a reference to an Earth fairytail. A girl gets blessed by a fairy godmother and goes to a fancy ball all dressed up, but her carriage is made out of a pumpkin, and the magic wears off at midnight. It's kinda been co-opted into pop culture to reference like, 'oh no, at x time I'll turn into a pumpkin, haha, better go!'

（ a pause. then: ）

I'm not going anywhere, just waiting for the clock to strike down. And hush about the cold and do what I say and you won't have to worry about a month.