Somewhere in a drawer here I have a Billion dollar note from some African nation from years ago. I think it roughly converts to about $100 here in Australia.
When I was there locals have draws full of everything from 10 billion up to the 100 trillion note.
They are utterly worthless now, except for tourists who pay $50 for them at Vic Falls.
For anyone curious, I kept a single bank note from all of the 35 countries I recently drove through in Africa [1]. There are some really fun ones in there like the Congolese Franc, etc.
They're worth a lot more now as collector's items, than they ever were as actual currency.
Just regular stamps.