I got so lucky there is an error on my bill and I won't say anything about it.
Why won't you tell them?
I don't want to pay more.
You shouldn't take advantage of the waiter's mistake. If there's an error on the bill, you need to tell him.
My mom told me not to ay anything.
Well it is stealing to know there is an error and not say anything. You should be honest with all of your dealings or people might feel you could do the same thing to them.