A childhood belief about fear of

There are two toilets in my house - one in the bathroom, and one in a little room off from the laundry. My 11 year old brother has only just started using the laundry toilet again after a 6 year fear that there are frogs living in it. In all fairness there is a creek behind our house, so we do occasionally get frogs near our house. To make it more fun, I have a toy frog with a motion sensor, so it croaks if you walk past. I'd put that in the toilet room just to scare him if he walked in.