With as many people as possible, form a circle. One person is chosen to start (#1) This person asks the person next to them (#2):
#1 Do you want to buy a duck?
#2 A what?
#1 A duck
#2 Does it quack?
#1 Of course it quacks its a duck.
#2 will then ask the person next to them (#3)
#2 Do you want to buy a duck?
#3 A what?
#2 (passes on to #1) A what?
#1 A duck
#2 (passes back to #3) A duck
#3 Does it quack?
#2Does it quack?
#1 Of course it quacks its a duck
#2 Of course it quacks its a duck
#3 Asks the person next to them (#4)
#3 Do you want to buy a duck?
#4 A what?
#3 A what?
#2 A what?
#1 A duck
#2 A duck
#3 A duck
#4 Does it quack?
#3 Does it quack?
#2 Does it quack?
#1 Of course it quacks it's a duck
#2 Of course it quacks it's a duck
#3 Of course it quacks it's a duck

The process continues with #4 asking the person next to them if they want to buy a duck and the messages are passes back and forth between that person and #1. The whole point of the game is that it sounds cool to hear many people repeat "A what" or "A duck" and so on. I give the credit of my learning of this game to my Warrant in British Columbia WO Quast. This year in Vernon she was my platoon warrant and she taught the platoon this game while we had nothing better to do. You were a great Warrant WO Quast!