August 23, 1994
A cheat option in the game is called "DK Mode", and once activated it distorts all characters' models making them with giant heads, shrunken bodies and bulky arms. Aside from a visual difference, this also affects gameplay, since with the models, also the enemies' hitboxes change in size, making it easier to perform headshots.
It is generally considered the easiest cheat to unlock, since it's unlocked by completing the mission "Runway" on "Agent" (the easiest) difficulty in 5 minutes or less.
The cheat's name comes from Donkey Kong's initials, likely because of the big arm being similar to gorilla arms, however the big head has nothing to do with Donkey Kong.
GoldenEye 007 was developed by Rare, that also developed the Donkey Kong Country games, so they included a reference to their previous works. It's unknown if Rare actually had the right to use elements from Donkey Kong, since its copyright are only held by Nintendo, but they probably didn't need it for such a minor reference.