Parents: in raising your child/children, what is or was the one rule of yours that he/she/they resisted the most?

Our rules were reasonable, so we had few problems. My daughter, however, would often break the sleepy-time rule. She would sometimes stay up until midnight reading. Mostly we gave her a break.

My son was a bad one for not doing chores. He was born lazy.

I didn't have a lot of rules; I concentrated on the important stuff.  The rest I played by ear.