Be good for nothing

A little boy says to his mother, "Mom, I'll be good for a dollar" The mother
replies, "I shouldn't have to pay you to be good, you should be good all the
time"
The little boy says, "OK Mom, I'll be good for 50 cents." The mother says,
"I shouldn't have to pay you to be good you should be good all the time.
The little boy says, "OK Mom, I'll be good for a 25 cents." The mother says,
"How many times do I have to tell you I shouldn't have to pay you to be good. You should be good for nothing, just like your father."