Find Lucky the Chicken 
In Casper's house, move in front of the bookcase. Shoot it with normal, fire, fire, 
ice, normal, fire, and super spirit blasts, in that order. A secret room will be 
revealed. Inside you'll find Lucky the Chicken, who will tell you part of a story. 

Secret room:
Move in front of the bookcase inside Casper's house. Shoot the bookcase with 
normal, fire, fire, ice, normal, fire, and super spirit blasts (in order). The will open 
to a secret room containing Lucky the Chicken.