Finally, a more shocking joke than "The Aristocrats." From, Man Says 7-Year-Old Joke Led to Killing, AP, April 26, 2005:

A man shot a former co-worker to death on Easter because he was offended by a joke told seven years ago, authorities said Monday.

Stanford Douglas Jr., 29, was arrested on murder charges Sunday after a two-hour standoff with police. He allegedly shot William Berkeyheiser, 62, three times in the chest and shoulder on March 27 at Berkeyheiser's suburban home.

Prosecutor Diane Gibbons said that Douglas told police he had been thinking about killing Berkeyheiser since 1998, when the two men worked at a Philadelphia nursing home and Berkeyheiser told a joke that offended Douglas.

The prosecutor would not say what the joke was.

The downside: This joke was clearly hurtful.

The upside: It was also clearly memorable.

Disclaimer: low culture does not advocate laughing at people getting killed. That would not be funny. In fact, it would be totally hack.