Ball point pens and you....

The inside of most ball point pens you will find in this world look about the same:
For this prank the only important piece is the tube that holds onto all of the ink.

The part labeled 'Writing part'

The top of that tube is actually open to allow air to enter as the ink is used up. So if you seal up the end of the tube, air will not be able to get into the tube as the ink is used, creating just enough of a vacuum to stop the ink from flowing out the tip of the pen. On the type of pen I am using the magic number is right about 100 words.

My boss is gone for the afternoon so I emptied out the pen holder on his desk and hauled them back to my office, where I have spent the last few hours taking them apart, super gluing the end of the ink tube and putting them back together. I then took them all back to his desk and replaced them into his pen holder. He will now experience a rash of pens running out of ink that he will not soon forget!

 Because I am in an odd mood todays hottie will also be odd...