For me, it is just a phobia. I have great bladder control because of it. Something about that black hole in the ceiling with that grill around it and the enclosed space.
When I went with Jimmy and Greg to the Great and Holy Appliance Burial Ground in Aberdeen, ND, we checked into a little mom & pop hotel that charged $29 a night, if I remember correctly. When I got to my room, as soon as I was in, I noticed a cord hanging down in the middle of the bathroom across the hotel room. I immediate knew I was in trouble. I barely survived the weekend, and openly cursed the Terror in the bath every chance I got.
Whole house fans aren't bad; I think the fear most kids have is that they will get sucked up into it. Big and noisy, the louvres open and up you go! Never to be seen or heard from again.
Note to self: call Steven King