This story told by a professor was presented as truth, but I have my doubts.
A high school teacher applied for work at all the high schools in his city, and was hired by an exclusive all-girls school to teach sex ed. Not wanting to have to explain to his wife that he'd be discussing sex all day with schoolgirls, he told her he'd been hired to teach sailing.
"But you don't know anything about sailing!"
"Teaching is easy--you just have to stay one step ahead of the class and you'll be fine."
The wife was unconvinced, but wanted to be supportive, so she went to the school on the first day of class and waited outside the door for class to end. Class let out, and wave after wave of girls streamed out, talking about what a great teacher they had. The wife stopped one of the girls and asked, "What did you think of the teacher?"
"Oh, he's great! He really knows his stuff--you can tell he has a lot of experience."
"Really? That's interesting--he's only gone twice, once he fell off and once he lost his hat."