Sometimes Hill family dinners include passing around the Prairie Home Companion’s “Pretty Good Joke Book” and everyone picking a side-splitter to read aloud. While this always amuses, we’ve found that tastes in humor certainly differ. British researchers recently proved that funniness depends on factors you’d expect, like the sex and national origin of the listener, and also by some surprising ones, like the joke’s length and the time of day it’s told.

The Laugh Lab is the brainchild of University of Hertfordshire professor Richard Wiseman and supported by the British Association for the Advancement of Science to explore the psychology of humor. Wiseman asked people to pass along their favorite jokes and to rate some jokes already submitted. Using a website, 40,000 jokes and two million ratings were gathered world-wide, except Japan, where joking is rare. About a third were offensive, and, since off-color humor wasn’t allowed on the site, Wiseman’s assistants, Helen and Emma, had to screen all the submissions. According to the Laugh Lab website, www.richardwiseman.com/LaughLab, “Within days, Helen and Emma had lost their sense of humor and gained the finest collection of rude jokes anywhere in the world.”

Fans of Monty Python will recall the episode about “joke warfare” set during World War II in which the British develop a joke so funny it’s fatal to listeners. The Germans retaliate with their own killer joke, which Hitler announces to his assembled troops: “My dog has no nose.” “How does it smell?” “Awful!”

The British “joke” in the sketch was actually German-sounding gibberish, but Professor Wiseman’s research has established the funniest joke in the world. Over 100,000 people from 70 countries submitted jokes, and funniness depends a lot on nationality. Americans and Canadians prefer jokes that make others look stupid, Brits, Aussies, and the Irish like word play, while Europeans have a penchant for surreal humor. Ironically, the Germans rated the jokes the highest approval rating of any nationality, but they had no preference for joke type.

The American Heritage Dictionary says the origin of “fun” is uncertain, but likely comes from “fonnen,” the Middle English word meaning “to fool.” The AHD is a “descriptive” dictionary, as opposed to “prescriptive” dictionaries. A good website on the subject, http://englishplus.com/news/news1100.htm, says “Descriptive dictionaries describe the language. They include words that are commonly used even if they are nonstandard. They will often include nonstandard spellings. Prescriptive dictionaries tend to be more concerned about correct or standard English. They prescribe the proper usage and spelling of words.” The AHD occasionally adds “Usage Notes,” and here it mentions that using “fun” as an adjective, as in “fun guy” or “fun time” originated only in the 1950s and is still grammatically questionable.

Now, the funniest joke in the world is beyond question. The Laugh Lab traced it back to Spike Milligan, the British comedian, musician and chief writer of the legendary “Goon Show.” “Two hunters are out in the woods when one of them collapses. He doesn't seem to be breathing and his eyes are glazed. The other guy whips out his phone and calls the emergency services. He gasps, ‘My friend is dead! What can I do?’. The operator says ‘Calm down. I can help. First, let's make sure he's dead.’ There is a silence, then a shot is heard. Back on the phone, the guy says ‘OK, now what?’”

Laugh Lab researchers found that jokes are funniest at 6:03 PM around the middle of the month and least humorous at 1:30 AM at the end of the month. They also found that “people who laugh more … have healthier immune systems than others,” and they cite another researcher “who estimated that a good laugh produces an increase in heart rate that is equivalent to ten minutes on a rowing machine.”

Libraries are known as repositories of information, but they also contain lots of entertainment, including 7-day DVD checkouts of hilarious films, like the complete Monty Python TV episodes. By the way, did you hear about the young lady who was excited about finding a book in the library titled “How to Hug?” Turned out it was volume eight of the encyclopedia.