As the title says, list the most absurd threat you've ever heard.

I remember when i was in highschool, some kid printed out a diagram of the interior of a nuclear bomb and would wave it at people, threatening to build it if they pissed him off. Oh man...

It's not going to be easy to top that...

No, that's not really to be topped. I wonder what's become of that kid now.

In high school we had a kid who threatened to have his brother beat up anyone who he didn't like. The catch? His brother was in 7th grade (we were in 10th), was the smallest in his year, hardly had any friends, was fairly timid and barely ever said a word. Otherwise a fairly decent kid, unlike his big brother.

I say "kid"; but he's around 26 now.

"I'm not buying the next Call of Duty unless you start innovating!"

yeah...

I've just remembered one from my youth, when a kid threatened to use a molotov cocktail against some other kids he'd had some disagreement with (yeah, my school was a bit rough!).

He actually went through with it and made the molotovs at his house, put them in a cardboard box and hid them near the school. What he didn't realize was he'd left his name and address on a delivery label on the box, which was found by somebody who called the police, who went to his house and promptly arrested him. Epic fail.

I was the president of the class in high school, and you won't believe the shit some of the fellow classmates came up with. For some reason, I was the go-to guy if anyone was missing that day in class. There was this one dude that was smoking weed, sniffing glue and probably something worse throughout the school year when we had him in class (transferred for the umpteenth time). Toilets were his favourite place for general horsing around, and it got so bad that "someone" had to investigate these ongoings (teachers were not allowed in the toilets reserved for pupils, they had their own locked WC). Some passive aggressive talks with the principal had me a volunteer (or else) patrolman for the floor of the building during recess. I didn't really rat out on nobody, but as you might imagine, paranoia is something that that particular guy was known for. His threats aimed against me were jaw dropping crazy, like he's gonna light himself on fire and run inside the laboratory we ha for chemistry class (I guess he thought that would make the school go boom??). He said he'll bite a cat's head off (there was a stray cat living around school). The best was that he'll go join the gypsies and learn how to course me (like many countries in the region, we have a healthy population of Roma people, but we don't generally call them gypsies and they're generally quite domesticated, so this was very racist on his behalf).
So one day, he goes missing. And then the circus started... Me and a fellow classmate were called to the principal, who was less than happy about this (he wasn't mad at us, but you always had the feeling that he will jump you if you don't act as shocked as he is). So we called his parents, who were surprised he just up an vanished (he was cracked in the head, but he usually didn't just go somewhere without telling someone, and very loudly at that). There was nothing we could really do at that point, so we just called the police and went about our merry ways.
Later we learned he was found trying to get into Hungary (???) and was detained by the border guard. He went by train and bus until he came close to the border, then went by foot. Why he didn't board an international train to Budapest or something similar we will never know. He didn't really come back to school, he got transferred again and hopefully got into class for special pupils or something.