Mr. Brown is at the doctor’s: “Doctor, I can’t sleep at night because I keep having to think about the crocodile under my bed.”
“I’ll prescribe some medication,” says the doctor. “You should be feeling better within a week.”
A week later, Mr. Brown is at the doctor’s again: “I can’t sleep, doctor. I’m still worried about that crocodile under my bed.”
“I’ll prescribe some other medication,” says the doctor, “but it’s very important that you stop thinking about the crocodile before you go to sleep, then you’ll be cured.”
A week later, the doctor is making a housecall near Mr. Brown’s house, so he decides to drop in and check up on his patient. As the doctor rings the bell, the next-door neighbour pops his head out.
“Are you looking for Mr. Brown?” says the neighbour. “I’m afraid he died yesterday.”
“My goodness,” says the doctor. “What did he die of?”
“He was eaten by a crocodile.”