With a possible global deflationary economic environment looming, some central banks have considered negative interest rates.
That is, buy a $1000 bond and get less than $1000 ... and no interest ... at maturity.
Read more about Negative Interest Rates at wikipedia if you like.

A related issue is trying to prevent citizens from hoarding cash, so as to achieve at least a Zero interest rate ... and hence the discussion about stopping the printing of large denomination notes -- $100 U.S. currency and its foreign equivalents.

In this article, the impact on gambling (re: an anonymous card counter) is discussed:
http://www.cnbc.com/2016/02/19/debate-over-the-100-bill-gamblers-and-negative-rates.html

Makes me wonder if some people might try to hoard $100 or higher casino chips, if Negative Interest Rates really materialize?
We know that chips are for "gaming purposes only" and are not to be used in this way. But if tried, the casino cages will be wary about cashing chips that walk in.
Federal regulations will probably follow, just like the casinos are responsible for enforcing and reporting on "structuring" cash transactions approaching $10K, due to money laundering possibilities.

For casino chip dealers, who may carry an inventory of $100+ chips, it may be an area to watch???

The whole idea of negative rates is counter to the logical "time value of money" economic theory, yet it's something that may be a reality from time to time.