In sickness and in health

A cross-post from my OnTheCommon.com blog: In sickness and in health
Our six-year-old granddaughter has made certain that we understand that, under no circumstances, will she tolerate this joke:

"How old are you?"
I'm six."
"Oh, you're sick. that's too bad. I hope you get better soon."

She got tired of it during the summer, several months before she turned six. She's already figured out that the family has a tradition of bad jokes. Some of the jokes she enjoys.

"Knock, knock."
"Who's there?"
"Interrupting cow?"
"Interrupting c.."
"MOO!"

Last weekend, we learned on NPR's "Wait Wait...Don't Tell Me!" that there's a word for this condition. Researchers have identified a mental condition and they've called it Witzelsuch.

"Why was 6 scared of 7?"
"Why?"
"Because 7 8 9."

Apparently, damage to the right frontal lobe can lead people to tell bad jokes and to do so inappropriately.
(You can read more than you ever thought you wanted to in this 2005 report by Taiwanese researchers here (PDF document).)

"Knock, knock."
"Who's there?"
"Interrupting fish?"
"Interrupting fish ..."

As we can see, the line between family holiday gatherings and pathology is pretty thin indeed.

"What does the farmer say when he discovers that his tractor is missing?"
"I don't know. What?"
"Where's my tractor?"