This Simple Office Prank

Find a coworker who is eating their food at the office in the morning (breakfast or something). Walk past them making an eye contact with them, and act like you are trying not to laugh. Leave the place with a smirk on your face. Keep asking them how the food was. Ask them how it tasted, and inquire if they find the food any different than usual. In the afternoon, ask them if they are feeling well. Tell them they look little pale.

That's it. Your coworker thinks you put something in the food to prank him or her.