Stuff a mattress of course.
Fill some old shopping bags and give them to a bag lady.
Find a poor single mom running out of options and give her a stack for free.
Mail 1,000 AR-15 80% billets and jigs to total strangers chosen at random from a phone book.
Fund a better library for the local community college.
Lots of options.
BTW, if it is American currency, the red ink was used on Cold War 'post-nuclear attack' currency printed at the emergency mint in Culpepper, VA, also the Gold Reserve Notes with Woodrow Wilson's picture had red ink on them. Probably others as well.