Go to options and watch the credits in text and not the video credits. Scroll all the way down until you see the credits for the mini-games. You should see on the screen "A" will appear -- press it.

Change the logo on a custom bike to "kingpin".

Complete the championship on champion difficulty.

Score 250,000 points in stunt mode.

Score 100,000 points in stunt mode.

Score 500,000 points in stunt mode.

Score 750,000 points in stunt mode.

Score over 1,000,000 points in stunt mode.

Score 325 championship points.

Score 375 championship points.

Score 300 championship points.

Score 275 championship points.

Complete every championship challenge.