My mother is quite an extraordinary lady. She has taught me to stand up for myself when I know I am right.
Case in point -
She would go to the local Walmart for groceries each week and each week her gallon of milk would ring up the wrong price. She would try to convince the cashier of the correct price and would finally resort to walking back to the dairy aisle, pulling the sign off the milk, and taking it to the cashier.
One Christmas I was home, walking through the dairy aisle with her, and she was telling me about how this had happened several times. She took me over to the offending milk.
I casually told her my observation, "Mom, that's the price for the half gallon." Oops:-)