Boss of the uber-creepy Shadow Temple in the Zelda game Ocarina of Time.
Upon reaching Bongo Bongo's lair, Link drops down a hole onto a gigantic drum. There, huge hands start to beat the drum, bouncing Link up and down. At first, all you can see are his hands, but using the Eye of Truth, you can also see his body (which, incidentally, is not attached to his hands). Specifically, you can see his single, giant, glowing red eye.
Beating Bongo Bongo is tough; it takes good timing and good skill with the fairy bow. Basically, what you do is hit both of his hands with the bow. This will freeze them for a bit, and prevent him from smashing you around with them. This task is made harder by the "floor" moving up and down, which throws off your aim; use Z targeting, because you will not be very successful (read: you have no chance) trying to hit them from the first person view. Also, stand near the edge of the drum away from Bongo Bongo, where the beating of the drum is less strong.
You can also shoot his hands as a defensive move, preventing an oncoming swat of his giant mit from reaching you.
OK, so his hands are (hopefully) stopped. Using the Eye of Truth to see him, shoot his eye with the bow. Since the hands aren't moving, neither is the drum, so it's an easy hit. Then go up and smash the hell out of his eye with your weapon of choice. I like to use the Biggoron's Sword, but the Master Sword or Megaton Hammer are also entirely suitable. Move fast because he won't stay down for long. Repeat several times, and collect your well earned heart container. Like most of the bosses, he seems to sometimes stay down for much longer than other times. Expect that much of the time you will only be able to get in a single hit before he recovers, but occasionally he will stay down through numerous hits; with luck it's possible to defeat him without having to disable him more than twice.
If you're fighting him for the first time, make sure to load up on fairies. It takes a while to get a good rhythm down, during which you will probably get hurt pretty badly.
This was the seventh boss from The Legend of Zelda: Ocarina of Time.
Previous boss: Morpha.
Next boss: Ganon.