i) Computer programs that screw up other people's machines, deliberately.
ii) What anti-virus authors allegedly spend their time writing so we all have to buy their anti-virus programs to remove the viruses that they allegedly wrote in the first place, thus making them rich, and us poorer.
3. A test designed to measure the stupidity of the average internet user by seeing how many of them open up infected attachments in emails, despite thousands of warnings not to be so dumb.
Hmm let me open this not at all suspicious naked girls screensaver attachment.... larks! My hard disk is suddenly reformatting itself. This is the work of a dastardly virus!