I Choose Sabotage!
I used to work in a warehouse where one other girl and I worked in one area together, except I did all the work while [Coworker] played on her phone all day in between occasionally yelling at me for stuff I didn’t do.
I’d hustle to get the job done, and I cleaned up on recognition from supervisors who saw me hustling. [Coworker] tried to blow it off when she got busted for slacking but never did clean up her act. She even occasionally had the nerve to tell me to “calm down” because I worked fast and she looked bad in comparison just standing there.
Eventually, I found another job, but I made a point of not bothering to mention it to this girl when my last day was.
I knew [Coworker] was going to be unpleasantly surprised by suddenly having to take over my job the next day, so I set her up to have the worst first day ever. I used up all the good packing tape and left out only the identical-looking stuff that tore easily, I hid the good tape gun and left out the identical-looking but broken one, and I unhooked the UPS scale. (When you unplug the scale, you have to restart the computer.)
I changed the password. Resetting the password was a massive headache because IT was terrible and inevitably took a couple of hours to do anything. The whole thing took less than thirty seconds, and I sabotaged at least half a day for her.
I later learned that [Coworker] got fired for not doing her job.