The irrational fear men often feel toward outhouses. Normally it stems from the associated fear that there may be an unseen alligator or crocodile somewhere below.
"Why did Elmer have to buy one of them newfangled INDOOR toilets?"
"cause me and Clem I heard he has Chompophobia."
"I reckon that's a mighty wise choice then. I heard something peculiar rustlin' in my own outdoor facility this morning."