There were some interesting virusses on the Amiga and Atari.
Wowbagger the Infinitely Prolonged -- Every 5 minutes it pops up a dialog box to insult you in a different way.
Or randomy switch some of your mouse axis around every couple of minutes, so now moving your mouse left makes the arrow go down, down becomes up, buttons switch around. Especially annoying when it keeps changing which direction goes where.
Or some that would intercept any disk-write operations and instead of the information you really try to save, substitute it with its own random text.
Wowbagger the Infinitely Prolonged -- Every 5 minutes it pops up a dialog box to insult you in a different way.
Or randomy switch some of your mouse axis around every couple of minutes, so now moving your mouse left makes the arrow go down, down becomes up, buttons switch around. Especially annoying when it keeps changing which direction goes where.
Or some that would intercept any disk-write operations and instead of the information you really try to save, substitute it with its own random text.