Dr Caractacus Penrose has discovered a whole new way of defining time, which he has called 'Freda Time' after his wife. The concept is expressed by the formula
Ft = (E + n)2
which, as Dr Penrose explains, means that Freda Time is equal to the square of the time that Mrs Penrose has promised faithfully to be ready to leave the house when they are going out somewhere, plus 'n' - 'n' in this context is any number except the one you're actually expecting.
Dr Penrose has said that it is theoretically possible that 'n' could be zero or even a negative number, but he says that in twenty years of marriage he's never bloody known that to happen.