The phrase refers to novelty currency, specifically a bill with a face value of one thousand dollars, featuring the likeness of Donald Trump. These are not legal tender issued by the United States Treasury. They are considered collectible items or gag gifts.
Items of this nature gain traction through their association with a prominent public figure and the potential for political commentary or humor. Their value lies in the novelty and collectibility, not as a recognized form of payment. Historically, novelty items tied to political figures have served as expressions of support, opposition, or satire.