In the sandcastle (Treasure Trove Cove) spell out "CHEAT" and then "GIVETHEBEARLOTSOFAIR". This will give Banjo-Kazooie and infinite amount of air.
Maximum Energy
In the Sandcastle (Treasure Trove Cove), Beak Bust in "CHEAT" and then: ANENERGYBARTOGETYOUFAR. This will give you the max of eight pieces on your life/honeycomb bar. Note that if you have Red Honeycombs already it will take them away. And if you turn off the system the code goes away and you'll have to redo it.
Infinite Eggs On the sandcastle floor (Treasure Trove Cove), type in 'CHEAT' and you will hear a moo sound. Then type in 'BANJOBEGSFORPLENTYOFEGGS'. It will not make a noise acknowledging the letters, so make it perfect!
Infinite Mumbo Tokens
Type in "CHEAT" at the sand castle floor (Treasure Trove Cove) and then enter: DONTBEADUMBOGOSEEMUMBO. You won't hear any sound, but if you did it right your Mumbo Tokens will increase to 99.
Infinite Red Feathers
Start by typing in "CHEAT" at the sand castle (in Treasure Trove Cove). Then type in "NOWYOUCANFLYHIGHINTHESKY". You won't hear or see anything when you type in the letters so make sure it's perfect.