Those were the days!
I think one of my earliest coding attempts was a sort of virus on the Archimedes, one of the cover discs had an antivirus app on it, which grabbed my curiosity so I wrote something (pseudocode, excuse me) like:
IF SYS$.Time = 09:00:00
Copy <random folder name>, <same folder name>
There were no checks in those days, so you could copy a folder into itself, which would cause an endless cycle of copying until the folder/FAT limit had been reached... or you pressed Ctrl Shift + Break