1) A computer
2) Half a brain (more or less)
3) A friend who
a. Has a computer
b. Isn't very good with computers
c. Has a sense of humor and won't react badly to pranks.
If you fit these criteria, you've got what it takes to pull some hilarious pranks that will leave you (and hopefully your friend) laughing.
Step 1: Set Up
right-click>open a new text document>file>save as>change *.txt to all files>save as prank.vbs
For this prank to work best, your friend can't be too computer savvy. So if your friend knows about stuff like VBS or other computer languages, it probably wouldn't be as funny. Also, this prank works best if your friends user on his Windows (yes, Windows is necessary) computer doesn't have a password. But even if your friend's user does have a password, variations on the prank will work.