Mad Jack

Mad Jack is a large seemingly insane jack-in-the-box from the game Donkey Kong 64.

After opening Frantic Factory's boss door, Tiny Kong finds herself in a pitch-black room with several glowing squares on the floor. Venturing onto one of these squares, Tiny is surprised when they rise into the air. Suddenly, Mad Jack appears from a large box that falls out of a nearby toy rejection chute.

Mad Jack first attacks by re-entering his box and hopping from square to square attempting to crush Tiny, who has to frantically jump to different squares in order to avoid the crazed toy. If Tiny manages to avoid Jack, he will then pop out of his box and begin hurling fireballs at the Kong. While Mad Jack is busy doing this, Tiny must press a switch on a nearby square. If the square the switch is on is the same color as the one Jack is on, then he will be electrocuted. However, Tiny will electrocute herself if the switch's color doesn't match Mad Jack's platform color.

Eventually, after being damaged multiple times, Jack will begin to hop around faster and also shoot energy blasts from his robotic eye, which create shockwaves when they hit the platforms. He will also turn invisible after taking four hits. In order to track where Jack is, Tiny must watch the sparkles that trail behind him when he jumps. Eventually, Jack will sustain too much damage, and his square (along with all the other squares) will fall, and Mad Jack will (humorously) crash into the ground below after doing a mock "wave goodbye". He is apparently destroyed.

Trivia

 * Mad Jack is commonly referred to as Quack-in-the-Box, due to a mistake in Prima's Strategy Guide for the game.
 * Mad Jack is listed as Junk-in-the-Box in the "Bosses" section of the Official Donkey Kong 64 Perfect Guide by Versus Books, adding more confusion to this character's name. Actually, that was his name when Donkey Kong 64 was still in development.
 * 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.
 * In fact, aside from Key 8 (The Boss Key in Hideout Helm), Key 3 is the ONLY other mandatory Key needed to complete the game. The other 6 keys only purpose is to open other levels. Since there are glitches which can access these levels earlier than intended, only 2 Keys are required to complete the game.
 * Speaking of glitches, if you could 'grab' Mad Jack during the fight, you could 'Quick Kill' him (Kill him before you hit the 5th switch). However, since we have no way currently to perform this on console, we are currently unable to use this for beneficial purposes.
 * The laugh heard during the battle is actually part of his theme's track. Said laugh along with his quacks were stock tracks originally vocalized for Donald Duck by his original portrayer, Clarence Nash, who had been dead for 15 years as of the time DK 64 was released. It makes sense, as throughout the battle, Mad Jack makes quacks similar to Donald's voice.