Ball Marker...............

Golfer walks into the pro shop at the local course and asks the golf pro if they sell ball markers.
The golf pro says they do, and they are $1.00.
The guy gives the golf pro a dollar.
The golf pro opens the register, puts the dollar in, and hands him a dime to use as the marker.


FYI: This economic model is also used by the U.S. Government.

H/T Doverthere