Deliver as many letters as you can, as fast as you can.
Paper, pens/pencils, something to use for start and finish lines, a box to put the letters in.
Gather your stack of envelops (with letters inside).
When the starter says "GO!" each player grabs one envelop at a time and runs to the box at the finish line, drops the letter in, and then returns to his or her stack.
Each player repeats this until all the letters are delivered, or they are too tired to continue.
The player who delivers all of his or her letters, or outlasts his or her opponents, wins. The winner yells "MAILMAN'S AWAY!"