One good prank to do to someone's computer is to change there Start menu so that is doesn't say Start. This is very simple yet dangerous (it is dangerous because your are editing critical files). Well before your start with this prank your MUST make a backup copy of "Explorer.exe". If you're are wondering it is in "C:\Windows\". Usually the best place to put the backup copy is in th folder "C:\Program Files\". The next step is to restart your computer and hold "F8" so you can run dos (this wont just run with a dos prompt). Or you can boot with a startup disk.
When your are running dos type in "cd=windows" and press enter.
Then type in "edit/70 explorer.exe" there should be a program that opens and it should be blue.
Use the "Page Down" button to move down to about line 2300. When your get that low you should be seeing sentences.
Use the arrow keys to slowly move down untill you see a part that says "S t a r t | T h e r e"...
(before the "S t a r t" there should be a club like in a deck of cards).
Put the curser so it is under the "S" in "S t a r t". Type in the first letter of the word your want to change it to.
Then press the "del" key under the "insert" key.
Do this to all five of the letters.
If your mess something up, relax. That is why we made a backup copy of "Explorer.exe". just go into dos. and type in "cd=progra~1" hit enter.
then type in "copy explorer.exe c:\windows". and press "y" to replace the existing file.