"I've just signed up to an online gaming tournament," said a boy they know.
"Me and my boyfriend are just hanging out watching TV," said one of their friends.
"I've sort of settled in at home," said another.
"I've just got too much work," said the last person they tried.
Everyone they rang was a sociable party-loving person. But something had happened. Was it the nights drawing in? The sudden cold? The gloom of recession sweeping the land?
"I mean, I can understand it if you're ill," said my daughter. "Or really, really tired. But if you're just sitting around doing nothing, wouldn't you be pleased if someone rang up and said, come on, we're going out?"
I have to admit that these days going out is a mixed blessing. Sometimes people my age get stuck into a sort of pre-recorded loop. You get all dressed up just to get a re-run of what you listened to last Thursday. Please, you think. Not again. Not the story about the AA and the car battery.
"Maybe there's too much pressure to have a good time on a Saturday night," said my daughter.
"So is it cool nowadays to sit around on the sofa in your PJs?" I said hopefully (because just at the moment, I'd quite like to disappear under a duvet and never emerge again. I'd like to blame this on the pressure of Christmas shopping, but it's probably because I'm too worried about the gas bill to turn the heating on).
"I don't think so," she said. "I think it's just not the night people choose to go out any more."
Does this explain The X Factor? Is this why restaurants are losing money? Should girls stay in, like they did years ago, and just wash their hair?
"Thursday's a good night for going out," said my husband.
So we're all stuffed, then. Christmas Day falls on a Sunday this year. And New Year's Eve is Saturday night.