Launder your money. One could argue it’s your civic duty according to a research paper:

• A standard American currency bill lasts anywhere between three and fifteen years depending on its denomination.
• Oils from human skin build up on the bills and eventually turn them yellow.
• Central banks print out new bills to replace 150 billion old bank notes every year.
• 150,000 tons of bills have to be shredded.
• All of this costs $10 billion.
• However the bank notes can be cleaned fairly easily, without harming the bill’s security features such as holograms by “superciritcal” CO₂ – saving the economy billions.

Read more about the study here.

Source: ACS