Like, get her to cut it up with a scissors, or have her burn it. Don't do it for her, but persuade her to do it. Discuss all the reservations she would have about it. Don't promise her anything in return, just work on her being willing to waste a valuable bill. Move towards the realization that the bill itself is not worth anything.
Money is energy.
Energy can't really be destroyed, you can always get it back. This works best with several people, but also with just two. Go into a closed room and simply throw all the money up in the air. Throw it around, make games with it, cover each other in it, stuff it inside your shirt, make it rain money all around, lay in it, roll in it, etc. Have a lot of fun with it.