A duck's walk is a waddle. To imitate it, turn your feet away from each other and take short clumsy steps that make you swing unsteadily from side to side.
Ducks aren't the only animals known to waddle. Penguins with their little tiny feet may waddle along the ice, though they move gracefully through the water. If your footing is unsteady, you might waddle a little too as you tread carefully. Don't confuse waddle with wattle. A wattle is the red bit of flesh that hangs from the necks of turkeys and chickens. Wattles waddle back and forth as birds waddle along.