You'll investigate crime scenes, unravel a mystery, and also unlock bonus content through passwords hidden in the game. (nintendochitchat.com)
Once you find enough cans of beer in each floor you'll unlock a bonus level where you will need to bear more times and unlock another collectible like bacon. (xboxgamerreviews.com)
To unlock the bonus games, you must find their respective portals (there are two in each world). (darkstation.com)