awesome idea!! That would be so funny. Or instead he could buy something with like a $5 bill at a target or something and ask for the change in pennies. Then he has to go to another store and spend all of those pennies.
I know it's cheesy, but what if we made John dress up in a ballerina leotard with fairy wings and so dancing on the street giving free hugs... Now, who wouldn't want to see that? :)) haha. Too cheesy?
For John: A choice. Either play Portal 2, all the way through, with only 3 mercy "HOW DO I DO THIS" calls to Hank for the entire game, or learn one of Hank's songs on guitar--one without chords given in a video, and no mercy calls.
For Hank: Cross stitch. Enough said. Or, stand on the street to the day, and ask for only pennies. Nothing else. He can't accept dollars, quarters, nickels, Yen, anything except pennies. Then at the end of the day, retreat back indoors (SAFETY!) and count them all/go to a store and buy something entirely with the pennies earned.