I could choose from the obvious $100 bill (which I didn't really keep lying around the house too much - they're inconvenient to use), the 20-euro note (lame - it doesn't look like real money), the 100-yuan note (more worried about residue on the note than anything else; snorting through Chairman Mao was a worthy idea), the 100-rouble note (which, like the euro, looks like play money) and the 10-pound note (or 5-pound, but that didn't seem as dignified). I didn't keep any larger bills because they could be exchanged for decent amounts of money, but small change is something I keep on hand just in case I'm going to travel. Given the "Mean Mr. Mustard" lyrics, I chose the 10-pound note because of the nostalgic musical resonance.