give one an inch, and he will take a mile

[give one an inch, and he will take a mile] If you give some peoplea little or yield anything, they will want more and more; some peopleare never satisfied.

I gave Billy a bite of candy and he wantedmore and more. If you give him an inch, he'll take a mile.

Thecounselor said to Jack, "No, I can't let you get a haircut untilSaturday. It's against the rules, and if I give an inch, someone willtake a mile."