|First appearance||Donkey Kong 64 (1999)|
|Portrayed by||Clarence Nash (stock recording)|
Mad Jack, also known as the giant springy box by Wrinkly Kong, is a large jack-in-the-box from Donkey Kong 64. He is the boss of Frantic Factory and the third boss of the game, or the fourth overall if one counts the optional Toy Monster.
Mad Jack is a metallic and green duck-headed jack-in-the-box. He has a brownish-green eye and a red, robotic eye. He is wearing what seems to be a scratched red smock. He also wears orange gloves with holes in them, and has coils for arms. He is contained within a colorful box depicting random shapes, and it has a blue rim.
After entering the boss door from Troff 'n' Scoff, Tiny Kong finds herself in a dark room with 16 glowing floor tiles, half is white and the other half is blue. They are evenly organized in groups of four and by pattern. Tiny must walk onto a tile to be lifted up to the higher floor. A toy box falls out of the toy rejection chute, hops on a few tiles, and Mad Jack pops out.
Mad Jack re-enters his box and hops between the glowing tiles in an attempt to crush Tiny. The tiles light up when Mad Jack lands on them. To avoid him, Tiny must glide between the floor tiles by using Ponytail Whirl to hop between platforms. Mad Jack cannot hop diagonally. After he jumps between nine platforms, Mad Jack pops out from his box and begins to throw six fireballs at Tiny. A blue switch each appears on a blue and a white tile. Tiny must attack Mad Jack by using Simian Slam on the switch on the same-colored tile as Mad Jack's. This causes the tile to electrocute Mad Jack. However, by hitting the other switch, Tiny Kong is electrocuted instead, causing her to lose half of a Watermelon in health.
In the second and third rounds, Mad Jack's behavioral pattern is mostly unchanged. However, for the second round, he hops from the floor tiles eleven times and only throws five fireballs before pausing. In the third round, Mad Jack hops around twelve times and only shoots out four fireballs.
Mad Jack only starts acting differently in the fourth round, after being electrified a third time. He still starts out by hopping from one platform to another, but afterward, instead of throwing fireballs, Mad Jack fires out lasers from his robotic eye, which then electrifies a floor tile. Tiny must avoid being hit by them.
After taking a fourth hit, Mad Jack becomes invisible and hops around on the tiles 15 times. In order to track where Mad Jack is, Tiny must watch the sparkles that trail behind him as he jumps. After being electrocuted a fifth time, the floor tile that Mad Jack is standing on collapses. Mad Jack then waves goodbye at the screen and falls down in a crash, destroyed.
Names in other languages
- Mad Jack was originally supposed to be a mini-boss called Junk-in-the-Box, had a design resembling a human clown, and was supposed to be fought in the R&D Room in Frantic Factory. Later in development, the Toy Monster became the new mini-boss for this world, while Mad Jack became the world's main boss.
- Mad Jack's gibberish ranting voice is taken from stock tracks recorded by the late Clarence Nash, the original voice of Donald Duck. The high-pitched maniacal laughter heard in his boss battle theme is also taken from Clarence Nash's stock recordings.
- Mad Jack's Boss Key is the only one in the game that does not unlock a world on its own. As such, players do not need to collect it immediately to advance. However, despite this, Mad Jack's Boss Key is still mandatory for completing the game.
- Mad Jack and King Kut Out are the only two bosses who do not emit shockwaves.
- If Tiny accidentally falls off the stage, she does not lose at the boss battle. Instead, a floor tile from the lower floor can return Tiny back to fighting Mad Jack.