1) A players health is such that upon being killed in a multiplayer game they explode into many gibs and giblets (peices of simulated flesh and gore). (Quake 1)
2) A game mode where every weapon (usually only a hitscan railgun/ASMD) instantly kills the player in one shot. (Started in Quake 2 and popularised as a mutator in Unreal Tournament)
3) Finding yourself at the bottom of a chasm/lava/force field and being instantly turned into gibs when you touch the bottom.
I was playng instagib the other day when I totally owned some guys when they lined up and I instagib'ed 4 people in a row!
So I was running around and a spammed a rocket into a door and it slapped this poor sucker in the face. I then jumped off the top of the level and instagibbed him with my railgun as I was falling. Dont think he had time to blink!
The act of being killed exceeding quickly. Standardly 1 shot. But in games lacking an 'instagib rifle' (or even anything resembling a gun) is usually taken to mean death in <1-2 seconds.
Unreal: The server had instagib enabled last night. Twas so chaotic my head was reeling after a few rounds.
Battlefield: That guy killed me as soon as I turned the corner.
Defense Of The Ancients: Care man, they will instagib you if you go too far alone.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.