Cool now I have two funny comics with this pun (RIP Something Of That Ilk, a vastly underrated web comic that died too soon)

Money laundering. Not even joking. Large denominations of cash is one of the more important ways of transferring value across borders for laundering purposes, which is why the largest number of bills in the most significant international currencies (USD and EUR, primarily) are in denominations mich larger than their day to day use value should suggest.