Jazz Jackrabbit Codes -

500 Credits:
Pause game play, then press Right, Left, Right, Left, L, R, Up(2), R(2), L(2). Note: This can only be done once per game, but can be combined with the other codes that have a similar effect.

1000 Credits:
Pause game play, then press Up, Down, Up, Down, Left, Right, L, R, L, R(2), L. Note: This can only be done once per game, but can be combined with the other codes that have a similar effect.

5000 Credits:
Pause game play, then press Up, Right, Down, Left, L(2), Right, Left, R(2), L(2). Note: This can only be done once per game, but can be combined with the other codes that have a similar effect.