Today I finished version 1 of a program that will run on the BBC computers in school. People keep stealing my floppy disks to annoy me so I decided to get my own back. If they try to use them I have a program that will now run when inserted into the BBC computers that I have written and compiled in Basic.I called in the HAHAs, because thats what it displays on screen - a never-ending loop of hahas with an optical illusion, meanwhile it uses up all available  memory so that the computer crashes.I spent the whole of my Christmas holidays, and most of every night since reading over the Acorn OS manual that I borrowed from the school computer classroom, and have found out that there are commands that you can use to over-write memory. Normally you shouldn't do that as it stops the computer working, but for the purposes of vengeance, why not.I ran several tests today at school and it actually works.The computing class today was boring so I spent most of it trying to work out how to make the program copy itself automatically on to the computer and also try to detect when a floppy disk is inserted and automatically copy itself back on to another disk, that way it will spread to all the computers without me having to copy it manually. The problem with copying it back is that I haven't figured out how to make it test if it already exists on the disk, so it displays a prompt asking about overwriting, so people would be aware of it.