This phenomenon often takes place in IRC. Some people are very adept at causing it. It happens when people are chatting away happily and someone (often innocently) interjects which shuts everyone else up and kills the chat.
<bob> so then we got dressed, took back the donkey and we never spoke of it again
<rod> haha sounds like fun
<dave> yeah wish i were there
<bob> no regrets <pete> hi all
...
...
.....
......
(large amount of time passes)
...
..
<pete> f*ck
<bob> nice chatkill you gronk
A Chankiller is a very intelligent but very, very rare species. Not many have been found in the wild. They have the ability to speak the language of which where they are found. A Chankiller is known to be loyal and be peaceful towards humans, but if you show any signs of aggression, or be rude to it, it will act back.