Just thought of another really evil prank you can do at school with the netsend program in my sig (if your school has rules against the messaging with computers)! I wouldn't recommend doing this unless you hate or want to get revenge against the person you 'do it to'.
The Prank:
1a. Bring my sig program to school on a disk and secretly get it on your computer. Do not, repeat, do not let ANYONE know that you have such a program if you want this to be effective and if you don't want to get yourself in trouble.
1b. Find the computer name of someone you hate at school. If the names are on the front of the computer then this prank is perfect for finding the name, and what should happen after you do it.
2. Think of the nastiest message you can think of (something that would even disturb administrators and something that you can't say here). Even better, make it some kind of threat (I wouldn't recommend doing that though). (You're really gonna like this next part...)
3. Send this message to
your own computer using the other person's computer name as the 'FROM' name when using the program! That's right! Send the nastiest message on the face of the earth to your own computer 'from' someone who you really hate and want to get in trouble!
4. Don't click out of the message just yet (that person's computer name will be on the message). Go notify the instructor/teacher or whatever that you got this message. DO NOT BLOW THE PRANK BY SAYING WHO YOU GOT THE MESSAGE FROM. THE TEACHER WILL IMMEDIATELY KNOW SOMETHING IS FISHY IF YOU SAY YOU GOT THE MESSAGE FROM A SPECIFIC PERSON. The teacher may have to search around for their computer, but when it is found, they will get in major trouble. They will try to deny it but nobody will believe them cause the teacher will have printed the message out or wrote it down as proof.
5. Immediately remove the program from the computer and make sure it is completely gone and not just in the recycle bin.
Again, if you only want harmless fun and don't want to get anyone suspended from school, 'water down' the message a little and don't make it a threat because it is illegal to send threats over the internet.
Use at your own risk.

I have not actually tried this yet due to a minor setback with me getting in trouble for messaging earlier this week (I shouldn't even really be on my computer right now cause I should be grounded).