Do you ever take coworkers combs/brushes/chapstick and rub them in the toilet while they're at meetings?

I am the secretary at my office, and some of the people there are mean. So when they go into their meetings, I rummage through their desks, sometimes take a comb/brush and go run it under the rim of the toilet, then put it back in their drawer. I also have done this with chapstick. Then i wait til I see them put the chapstick on and they don't know that it was covered in old urine, etc. Do you ever do stuff like this at work? Besides getting fired, could I get sued or only just fired?