My brother and I used to play Monopoly continually as children. Anticipating the banking crisis by several decades, we would borrow huge sums from the bank to spend on sub-prime mortgages. The sums were so large that we used the spare title deed card as a promissory note for a gigantic amount of money. (Incidentally, this is how we learnt from my dad what a million was.)
Our mum didn't like us engaging in this large scale lending because it made the game too harrowing. So we hid money and the promissory note under the board. That's why you can see in the top right hand corner it says, 'noaty thing'. It could mean 'naughty thing'. I think it means 'noughty thing', meaning 'thing with a lot of noughts'.