This one comes to you courtesy of the tip line, and I have to say, some of you out there in interwebz land are more evil than I am. 

This is a simple physical attack.  You go to the water cooler, take those cups that hang on the side and dip the rims of them in Tabasco sauce.  Then it is as easy as letting them dry and putting them back.  Later on some thirsty people will find that the water we have here has a kick.  Enjoy!