With this trick making zennies can be very easy. Just 
go to the Apple Market and look for a small yellow can 
near the entrance. Kick the can over teh counter and the 
shopkeeper will give you a good 1,000 Zennies for picking 
up litter. Leave the store and go back in and the can will 
reappear and you can do the trick again. Repeat as much as 
you want.