Add salt to the sugar.
An old and obvious option the ratio of salt to sugar is what really matters. The goal should be to add enough salt that it ruins the beverage, but isn’t too distinguishable. Experiment with your own homemade blends before unleashing it on the office. If you are really interested in ruining someone’s day, unleash as much salt as you wish into the sugar supply. It will be jarring for at least one person, but may not have as many wide reaching effects as desired.
For those who are really invested in ruining the beverages of others, empty the contents of sugar packets, fill with salt and reseal. If you thrive on danger, try secretly adding salt to drinks that are already poured and stirred. With slight of hand you can make yourself the office Chris Angel. This way the target of your salting will have to imagine that they did it to themselves. Getting the focused attention of the office prank monkey does usually involve some culpability.
Hope for a spit take.
Historical Note: Soldiers in ancient Rome were paid in salt, which is where the term salary comes from. Salt has played a role in the employee’s life for so long, it is a shame to end it today.