Mothers advice to son

A mother eager to teach her small son good manners told him one day to offer his seat to any lady if he finds one standing in the bus.
A few days later the son came back and complained to his mother that a lady had slapped him in the bus to whom he had offered his seat.
Mother: How insolent these ladies have become now a days...
by the way where were you sitting, son
Son: On my father's lap...