Thank you to ANDY4U2CALL@webtv.net for the following codes in yellow, and gedowski@yahoo.com for the codes in green.

NXPEKA: weird music (sound test).
EPOAKO: weird sounds with the music (freezes often).
NXPALA: different music variation.
NXOELA: mixes up music, enemies move
backwards, Trevor can moonwalk.
XXPOPO: another music mix.
EAAEKK: combine with XXPOPO for some cool tunes. Or use it on its own.
AEAAEE- Very cool opening tunes, awesome music on enter name screen, (go to sound test first & then go back to hear note scales).
EPPEKO- Different drum sound.
GAGALA- Different music, very awesome fire cursor, Trevor has incredible jumping motion, you won't believe your eyes! Check this out NOW! Game usually freezes early in 1st level.
GALAGA- Messed up effects and weird sound/music in password mode.
AEEEEE- CV theme on the bells. Cool music
ANEEEE- Cool SFX, no high pitched ringing this time
AEEEEA- Old school bass
KVAVPY-when you start a new game, but before the 1st stage starts, a debug menu pops up. The 1st 3 numbers pertain to what stage you want to start on, and the last number pertains to who you want as a partner. Use select to toggle between the numbers, A and B buttons to increase and decrease the numbers, and start when you're done.