[Young Werther]

Harde Har!

[Lucky9teen]

Also see this Thread

[theDentist]

take saran wrap and place it tight beneath the seat. Hilarity and the need for cleaning supplies (and a shower) ensues.

[Rebelbase]

Here’s one I pulled 20 years ago:

http://www.freerepublic.com/focus/f-news/1606931/posts?page=34#34

[CrazyIvan]

I replaced the honey at the breakfast table with STP. Dad was not amused

[DelphiUser]

Take a post-it note cut in half. Write April fools on it then stick to the bottom of any optical mouse.

The mouse appears to be non functional until turned over, message read and note removed.

I came to work early an did this to every mouse, then went for dough-nuts... funny, nobody would eat them

[frithguild]

Post a sign on the copier at your office:

This copier has been upgraded.
• Linguistic Module 4.01 has been installed.
• Voice Commands have been enabled.
1 State your name (for diagnostic purposes only)
2 State the desired function keyword:
Allowed keywords include:
COPY, COLLATE, STAPLE, ETC…
3 State the number needed, then say START.
PLEASE NOTE: The module is in learning mode and the user may need to repeat the command until the voice is recognized.

[lafroste]

Here's my best: Buy one of those musical greetings cards. Carefully remove the musical player (about the size of a quarter). Hide in the office of your target and turn it on.

10 minutes - no symptoms

20 minutes - actively looking but trying to look cool while doing so.

30 minutes - actively searching with no pretense now.

45 minutes - ripping the office apart, pulling on hair, etc.

60 minutes - time for the men in the white coats cause he's a drooling mess.

It works great.