A distributed subliminal urban practical joke.
Get that $5 you were planning to spend on junk-food or a movie, take it to the bank, and ask for it in pennies.
Out on the street, pause to appreciate the heft of the coin-rolls: ten finger-like columns, two hands of pure metallic value. Take a seat somewhere, break a roll open, and look at a penny. Appreciate the reliefs of Lincoln (by V. D. Brenner) and his memorial (by Frank Gasparro). You're holding the smallest unit of the most widely used currency on earth: a single share of the Pax Americana. This 2.5 grams of copper-plated zinc is the seed of every number with "US$" before it, and its tens of millions of cousins have spread more evenly around the earth than any other human artifact. With it you can give someone a penny for their thoughts, put in half of your two cents, or shout "Nothing! Not one red cent!" with a prop. But it's almost exactly free.
Keep your pennies with you, and, next time you're in the urbs or the 'burbs, lose them on purpose. Put them everywhere. You can hold about a dollar's worth in one hand and pop them off with your thumb discreetly in the middle of crosswalks and on the hoods of parked cars. Put them where they'll be found by panhandlers, bankers, and children. Hide them under and behind things. Make mandalas and portraits on the sidewalk. Throw a handful across an empty park at night. Roll them down hills. Drop them, with a little show of care, in plain sight of passersby. Prop them up against shop windows. Balance them on road reflectors. Tape them to phone poles. Toss them into crowds.
A few hiding-spots are especially gratifying. Try tucking one between the heads of double parking meters, where motorists will wonder if someone was trying to be generous by leaving them ten seconds of parking time. Who will expect a cent lying on a supermarket shelf? Public bathrooms have a certain something; people spend most of their time in them trying to forget that the space has been used by hundreds of strangers, so finding an anonymous present on the faucet could be quite stirring.
I figure a properly-placed penny is worth at least a dime. You, the Placer, get joy worth $0.01 from the thrill of deliberately losing money, $0.01 of self-congratulation for being charitible, $0.02 of fun in hiding it, $0.01 out of imagining how it might be found, and $0.02 worth of good memories every time you pass the spot where you hid it, minus $0.01 for the penny — a net gain of six cents. The Finder will get $0.01 of money plus perhaps $0.01 of joy out of having found a penny, $0.02 of wonder at finding it in such an interesting place, and $0.02 of social bonding if they tell a friend where they found it — again, a gain of six cents.
(These figures, of course, are averages, and don't take into account several nebulous factors. For instance, the penny might be found by an extremely busy person who doesn't take the time to ponder the provenance of free money — but, contrariwise, it might make the day of a small child — then again, it could well be scuffed into a storm-drain or buried by falling leaves, never to return to humanity. In the big picture, it may be that learning to wantonly toss money around will lead you to poor spending habits, but, conversely, free money might well lead the Finder to reflect on the nature of earning, spending, and wealth. For myself, the sheer fun of going out and doing something this stupid on purpose outweighs all doubt. It is, perhaps, the ill-advisedness of giving money away that makes it so healthy; there is excellent fun to be had by being this wasteful with a small group of friends.)
Once you're in the groove, you'll find many interesting variations. Many alternative types find satisfaction in most strangers' refusal to take a directly offered penny. Instead of a quarter, give buskers twenty-five pennies counted out with laborious precision. Get fifty wheat-back cents for a dollar from a coin shop, mix them with your pocket change, and see if anyone notices. Try hiding nickels, but be warned: we regard pennies as pure whimsy, but nickels are worth just enough to be taken seriously. The point, after all, is money without greed.