Conker's Bad Fur Day 

Barn Boys chapter 
Enter "PRINCEALBERT" as a code to unlock the Barn Boys chapter.

Bats Tower chapter 
Enter "CLAMPIRATE" as a code to unlock the Bats Tower chapter.

Sloprano chapter 
Enter "ANCHOVYBAY" as a code to unlock the Sloprano chapter.

Uga Buga chapter 
Enter "MONKEYSCHIN" as a code to unlock the Uga Buga chapter.

Spooky chapter 
Enter "SPANIELSEARS" as a code to unlock the Spooky chapter.

It's War chapter 
Enter "BEELZEBUBSBUM" as a code to unlock the It's War chapter.

The Heist chapter 
Enter "CHOCOLATESTARFISH" as a code for extra money and to unlock The Heist chapter.

All chapters and scenes 
Enter "WELDERSBENCH" as a code to unlock all chapters and scenes.

Fifty lives 
Enter "BOVRILBULLETHOLE" as a code.

Easy mode 
Enter "EASY" as a code.

Very easy mode 
Enter "VERYEASY" as a code.

Debug mode 
Enter "XFYHIJERPWAL IELWZS" as a code.
This code allows the game to be played in debug mode on Nintendo 64 development systems.
It has no useful function in the retail version of the game.

Play as Conker in multi-player mode 
Enter "WELLYTOP" as a code to unlock Conker in multi-player mode.

Play as Neo Conker in multi-player mode 
Enter "EASTEREGGSRUS" as a code to unlock Neo Conker in multi-player mode.

Play as Gregg the Grim Reaper in multi-player mode 
Enter "BILLYMILLROUNDABOUT" as a code to unlock Gregg the Grim Reaper in multi-player mode.

Play as Weasel Henchmen in multi-player mode 
Enter "CHINDITVICTORY" as a code to unlock Weasel Henchmen in multi-player mode. 

Play as Cavemen in multi-player mode 
Enter "EATBOX" as a code to unlock Cavemen in multi-player mode.

Play as Sergeant and Tediz Leader in multi-player mode 
Enter "RUSTYSHERIFFSBADGE" as a code to unlock Sergeant and Tediz Leader in multi-player mode.

Play as Zombies and Villagers in multi-player mode 
Enter "BEEFCURTAINS" as a code to unlock Zombies and Villagers in multi-player mode.

Use frying pan in multi-player race mode 
Enter "DUTCHOVENS" as a code.

Use baseball bat in multi-player race mode 
Enter "DRACULASTEABAGS" as a code. -From: AcidMan000@aol.com

New death animation in single multi-player mode 
Enter "SPUNKJOCKEY" as a code. Use a chainsaw or katana to cut a Tediz head off 

in the War level for a Matrix-type death animation.

Funny comments 
Enter an obscene word as a code to hear funny comments.

Infinite tails 
Find the hook on a sign in level 2. Intentionally die to start the hook tutorial.
The hook will now have a tail for extra lives. Take the tail and return to level 1.
Return and another tail will appear on the same hook.
Repeat to get as many lives as needed.

Skip introduction sequence 
Press Reset as soon as the Nintendo 64 is tunred on.
Press Start when Conker cuts the Nintendo 64 logo to advance to the starting menu.

See Banjo's head 
Turn to the options screen in "Cock and Plunker".
Look above the fireplace to see Banjo's head.

See Kazooie's head 
Go to the chapter selection screen and play any level.
Before the level starts, you will be able to see Kazooie's head on the umbrella-like object when the screen fades.

Conker being bored 
Let Conker stand without doing anything and he will start to do things like play 
with a yoyo, drink something, and pull out a Game Boy.
When he pulls out a Game Boy, press R to go into first person mode to watch him play Killer Instinct.
Do not move or Conker will put it away.