My idea was a worm that just torrents random shit and dumps it on your desktop like a cat bringing you a dead bat with "I broughted you a pwesent w" energy.
I did one similar! Used autohotkey to hide the task bar at random intervals and pop up a warning that said "system out of memory". Only way to get it back was autohotkey or a reboot. It would restart daily and on login so it would keep happening. And I hid it as "Nvidia game scanner service.exe" in the Nvidia bloatware folder so it looked innocent. Had a good laugh about that one