how i get a bonus ?

[Tad Carlucci]

Bonus K$ are the money sent in from the Dock.

The strange terminology comes from the way things were developed. First came the Menagerie function, and K$, which can be used to obtain Special Menagerie collection cats; then came the Cattery and the Dock and your ability to convert L$ to K$ and use those "bonus" K$, as well as those from sending cats to the Menagerie, for supplies like food and milk.