Teenagers don't do anything in moderation. A lie-in means sleeping till 2pm. A snack is a whole packet of spaghetti with all the cheese you were saving for supper. A quick burst of online gaming means Sunday evening, in its entirety, is wiped off the calendar.
(Once, on holiday, my eldest decided to drink a whole pot of real coffee after everyone else had gone to bed. He stayed up all night watching the Lord of the Rings trilogy back to back and was still buzzing when we emerged for breakfast. "But nobody told me," he said, wild-eyed and sweating.)
This lack of moderation is, of course, what makes teenagers so special. There are downsides (getting drunk, eating all the chocolate in the house). But you've got to admire the fire and passion that makes them challenge conventions and experiment with new behaviour.
Except when it comes to celebrating Halloween twice in one year.
"Where are you going?" I said to my daughter on Saturday night as she appeared in the living room in black jeans and purple lipstick.
"Halloween," she said.
"But that's not till Thursday."
These days, I hate Halloween. I feel mean and curmudgeonly. But I can't get excited by small children hammering on the door and looking all disappointed when I give them a KitKat.
My daughter pursed her purple lips. "That's just the actual day. We're celebrating early."
My heart sank. Teenagers plus Halloween spells mayhem. Or at least it does in my part of south London. You never know, from year to year, what particular brand of lawlessness will be in fashion. It was raw eggs one year. Flour bombs another.
At least, I thought, trying to look on the bright side, celebrating early means getting it all out of the way. Once they've roamed the streets frightening themselves to death, we can all rest easy in our beds for another year.
"And next weekend," I said, "it will be fireworks, won't it?"
She put on her coat. "And a Halloween party."
I looked at her in horror. "But I thought you said...."
"That's what's so good about it being on a Thursday. We can celebrate both weekends."
Oh joy. Oh joy.