A childhood belief about fear of

When I was around seven or eight, I used to believe that if I stayed in the toilet for too long after I'd flushed, piranhas would come out of the toilet bowl and eat me. I think this idea came from a dream, which I remember clearly - I was in a boat with two strange men and a woman, none of whom I knew. Piranhas were swimming around under the boat, wearing pink bows on their heads and wellies on their fins. We dropped a cow in the water, and the piranhas ate it in two seconds. Then one of the men fell in the water and the piranhas ate him.
After this dream, I had a system worked out - the piranhas would come out from a reservoir, up the river, up a pipe and would eat me. I also believed that a dead cow would come out of the toilet bowl when the piranhas were having a day off, and kill me to avenge itself.
I still don't like to stay in the bathroom for too long.
xDD