It's late at night, and you hear a toilet flush. When you check, no one's there, so you go back to sleep. An hour later, it happens again. Two hours later, the same thing occurs. Again and again thereafter you hear a mystery flush. Since it's April Fools' Day you're suspicious. Does the toilet need a fix or is someone playing tricks? If it requires fixing, it's an easy repair. Water likely is slowly seeping from the tank into the bowl. When the water level gets low enough, the tank refills itself as it would have had it been flushed. The problem is the soft rubber flapper (that lifts and releases water flow) isn't sealing the flush valve at the bottom of the tank. This lets water through. The solution: (1) replace the rubber flapper; (2) check the valve seat for cracks and debris; and, (3) either clean or replace the valve seat ring. This will end these annoying phantom flushes.