A Toilet Flush Monster climbed out of my toilet whenever I used to flush at night. If I could get back into bed completely covered by a blanket before it fully climbed out (i.e. the tank filled in with water and stopped making noises), then I was safe. All lights had to be off the whole time, or else the monster could see me.

Don't laugh.

In one of my childhood's flashes of clarity, I must have wondered how I knew about the monster if I'd never actually seen it. So one day I watched the toilet flush, and no monster came out. I checked with the lights off, and light on, and nothing. Since then, I could go to the bathroom with lights on, for once.

Well, I defeated the monster. But I'm still a little afraid of using a flashlight at night, or stepping into the floodlight when there's a lot of darkness around. So the monster vacated the toilet, but continues to haunt me.

PS: For fear that my statement may be misinterpreted: I don't actually believe in the monster, duh! But I still show symptoms of the Toilet Flush Monster disease.

My own story of rationality overcoming fear involves, ironically, belief in ghosts. Long after I was a devoted rationalist, I still had a lingering fear of hauntings and ghosts. You see, I'd been constantly told as a child that I had lived in a haunted house when I was too young too remember.

There was documented proof. Every time we had occasion to pass by the house, it would constantly have a 'for sale' or 'for rent' sign on it over the course of years, changing hands every time. Two suicides and a number of deaths occurred there (including one double suicide/homicide) and my mom had newspaper clippings. Surely, even I couldn't contest that.

More salient were the personal stories. Everyone in the family would see apparitions in the night, like nightmares made real. Other times the whole family would all be overcome by fear simultaneously. They would sense spirits but feel paralyzed to move. They'd see other people in the corner of their eye, but they'd disappear before they could talk to them. Sometimes they would lose time as if possessed in a trance. Othertimes the spirits would possess members of the family and make them do odd things or unable to move well or at all.

So while I had grown up a rationalist, I still had a phobia of spirits and haunted houses. It took finally doing research on that house to understand what really happened. You see, carbon monoxide poisoning has all of those effects. It was mysterious in magical back then, but looking back it's just sad. Several lives lost, other lives ruined, and massive negative utility all because somebody probably messed up the gas piping and nobody thought to install a CO detector. And part of that was because idiots (my family included) thought the place was haunted instead of trying to solve an unexplained problem with science.