The act of killing a joke before it comes to fruition. Typical situations involve a third party ruining the timing of the joke, or the expectation surrounding the joke growing exponentially in such a way that when actually said, the joke is rendered unfunny by contrast with the listeners expectation.
"hahah right, but no one really likes to drive a Mini, it's like having..."
"Oh, just remembered, don't forget to give me that money you owe me."
"...sex with a midget, damn you idiot you just aborted my joke!"
"If you don't have any money you should try to say... ah forget it"
"It's a geek joke, it's not even very funny"
"Now you have to say it"
"No way, forget it"
"Say the joke already", "C'mon dude we're waiting!"
"Ok, jesus, you should try to say "sudo give me a beer"
"Don't look at me, you guys made a total joke abortion"