Related to the second one, I made a batch file that opened a whole bunch of pictures of cows in paint, then opened a copy of itself, then looped, so that infinitely many cow pictures would open, and it would open exponentially more of them per loop as time went on. It would usually bluescreen a school computer in about 15 or 20 seconds. Did the same folder icon thing.

I put it in my student drive as a landmine to protect myself after I had told a lot of people that the admin had fucked up and all students were able to read and write to each other's drives. This had rapidly become bedlam, so I hid all my stuff in a maze of hidden folders and shortcuts that had copies of this cow file as dead-ends.

Unfortunately, people who ran into this cow file thought it was cool, so they started dropping it into each other's drives to blue screen each other's computers. Eventually, the school admin figured out what was happening and fixed the privileges, so everyone stopped being able to write to each other's drives, but they could still read. Weeks later, when searching for games in someone else's files, he accidentally triggered the cow file, crashing his computer and apparently losing dozens of hours of unsaved work.

Since all they'd copied was a shortcut, it was still pointing to a file in my drive, so I was the one who got in trouble. Which is fair. For months my computer privileges were taken away lol