super-careful, frugalistic, extra-tally-conscious
What Mary Poppins has to be whenever money is tight.
The movie got it all wrong --- the Banks family had not been having trouble with mean/colorless nannies; the nannies had all just been over-indulgent of the children, and so Mr. Banks hired Mary Poppins to teach his little ones about self-denial, willpower, and wise money-management --- Mary taught them to be "super-careful, frugalistic, extra-tally-conscious" when necessary.