Snowboard Kids 

All snowboards, characters, and courses 
At the title screen, press Analog-stick Down, Analog-stick Up, Down, Up, C-Down, C-Up, L, R, Z, Left, C-right, Analog-stick Up, B, Right, C-Left, Start. If you entered the code correctly, Nancy will laugh.

Play as Shinobin 
Earn a gold medal on the "Ninja Land" bonus course.

Quicksand Valley course 
Earn gold medals on courses one through six. Then, a new snowboard and the Quicksand Valley desert track will become available.

Silver Mountain course 
Earn a gold medal on the "Quicksand Valley" bonus track. This will enable the Silver Mountain track and a special ending sequence with all characters.

Ninja Land course 
Earn a gold medal on the "Silver Mountain" bonus track.