Amusing bugs.

[Valigarmander]

No, not that kind.

Monster infighting is a major component of Doom. If a monster is accidentally damaged by another monster's attack, it will retaliate and the two will fight. This extends to explosive barrels: if a monster's attack causes a barrel to explode, any monsters hurt in the explosion will turn on the one whose attack resulted in the explosion.

In the earliest versions of Doom, if a monster is hurt in a barrel explosion caused that it cause, then it will target itself. Monsters that have only ranged attacks will simply flail around and shoot in random directions, but monsters with melee attacks will instead claw/chew themselves to death.

[The Amazing Tazy Ten]

There's this one.

Basically, by holding back then forward before pressing fierce and roundhouse with exact precision this can happen. You can also reverse it, but again exact precision.

Get it down and you throw your opponent's soul about until they're knocked out.

[Artemis009]

The bug itself is pretty tame for '06, but it is still somehow one of the best clips on the show.

[X-3]

NSFW (but only because you shouldn't look at videos during work )

[Auron]

Perhaps one of the most infamous bugs of all time, everyone has probably seen this. But it will always put a smile on my face:

[Sim Kid]

^ Honestly you can just post almost anything from a Bethesda title. Especially for Skyrim - they intentionally left some bugs in the game if they were funny.

STALKER had some very amusing bugs... though they are far less amusing when you're actually playing the game and are trying to get the true ending. The game is so unstable, it can change states when you quickload and quicksave. I've had:

* people suddenly turn up dead for no apparent reason
* Said people being treated as "alive".
* People who were friendly suddenly turn hostile on me.
* Quicksaved before talking to someone, then quickloaded and suddenly that person is lying on the ground dead yet the game acts like they are still alive.
* Enemies eating bullets at point blank range
* The game telling me that people don't like when you point guns in their face... when MY GUN IS PUT AWAY
* Somehow getting disgusting amounts of money, that quickly vanishes the second you decide to go on a spending spree.

[Valigarmander]

Dwarf Fortress is an absolute gold mine for bugs.

• Animals being able to rent rooms.
• Pets and livestock discovering religion and worshipping dwarven gods.
• Traders arriving with bags filled with magma, inadvertently burning down much of the surrounding landscape.
• Fruit gatherers getting stranded and eventually dying of dehydration atop stepladders after the tree they were in the middle of gathering from is chopped down.
• Fireproof constructions made out of ice.
• Dwarves getting stuck in an infinite loop trying on different gloves or boots.
• Magma crabs drowning in magma.
• Vampires attempting to ward off suspicion by framing infants or pets for their killings.
• Dwarves spontaneously melting when caught in the rain.
• Elephants and other large, grazing animals starving faster than they can possibly eat.
• Spit coming out frozen.
• Dwarves who have had their eyelids torn off using soap to wash their eyes.
• Farmers grabbing furniture and planting them as if they were seeds.
• Pinching being powerful enough to sever heads.
• Being able to place things like stones, weapons, vomit, corpses, or cats into a mug and then drinking the contents.
• Dwarves being able to throw things without having usable arms (or legs).
• Bandit gangs and armies composed of nothing but domesticated animals.
• Dwarves jumping down a well to their deaths because it's been designated as a meeting area.
• Cats wandering around in taverns, getting booze spilled on them, licking themselves clean, and dying of alcohol poisoning.
• Executioners who are unable to wield a weapon instead biting the condemned to death.