Reward: Obsidian Axe, 2 Silver Keys, Chicken Hat, Chicken Expression.
In the south-eastern part of Oakvale you will meet a man who's having trouble with a ghost haunting the place where he's holding the Chicken Kicking event. Agree to help him and go to the nearby beach. Talk to the ghost. He'll ask you to find the buried treasure of his and give it back to his wife. The treasure is to the left of the pier on the western beach. Pirate's wife is standing a little bit further to the west. When you return to the ghost, he'll disappear and tell you there's a reward for you buried under the axe of the statue in Memorial Garden (Silver Key + Obsidian Axe).
Chicken Kicking supervisor will take his place and encourage you to take part in the competition. You can win some cool stuff in here: chicken expression, a silver key and a rather avant-garde hat. The goal of the game is to kick chickens (doh) so that they fall on the right fields of the 'board'. Quite easy, indeed.