We sweep the house carefully room by room checking for calendars. Sometimes people keep their calendar in weirdest places so you have to be thorough, checking under the bed, inside the closet, in your loved one's underwear drawer. We check the calendars and adjust them to the right date, putting them back afterwards.
The tricky part is that we cannot be uncovered. Ever. When one of us gets caught the best he can do is act as a simple thieve and go to prison for a while.
So the next time you find yourself standing in front of the calendar thinking: “Hmmm.... Who moved the little sliding window to the right place? Was it me before going to the bathroom? Was it my mom? No, she's still sleeping.
So it was dad. But I haven't heard him entering my room... oh well...
It was probably me then.”