On the phone, around 12:30 in the morning.
Becca: So, when are you coming home for Christmas?
Me: The 22nd. And my flight gets in at like midnight, so I'm guessing Mom will make you and/or Dave pick me up.
Becca: Ooh, okay. Oh! And then afterwards, we should go do something crazy. Like... get milkshakes!
I laughed so hard I cried.