Callahan's Crosstime Saloon was an invention of sci-fi author SpiderRobinson, a sort of a cross between the TwilightZone and DavidLetterman.

Here are two "shaggy dog stories" from Groaner Night competitions at Callahan's:

The WWII British spy Harry Lime was on board a US submarine en route to his next assignment, when he unexpectedly began seeing double vision.  The sub was off the eastern US coast, and so plans were changed so that Lime could be seen by a doctor at Walter Reed Hospital in Bethesda, Maryland.  The sub's captain was suspicious that Lime was actually faking the illness, presumably to go visit a former flame in Annapolis.  When the sub pulled into port, he ordered the spy, "You go straight from the sub, Lime, to the Reed oculist!"

No doubt you've heard of the South Seas island home of the rare Foo-Foo bird, and of the unfortunate ornithologist's assistant.  (The ornithologist and his assistant were both shat upon by a Foo-Foo bird they were watching - before the ornithologist could give warning, the assistant wiped the offal from his jacket, and was immediately struck by lightning and killed - "If the Foo-Foo sh*ts, wear it.") A follow-up expedition was nearing the island by boat when a sudden storm capsized the ship, and the passengers and crew had to swim to shore.  One naturalist and his assistant found themselves swimming among a pod of seals.  The naturalist watched while his assistant, following one seal, accidentally swam into the seal's excrement.  Unfortunately, when the assistant wiped the feces from his suit, he was immediately struck by lightning and killed.  When the naturalist reached shore, he had signs posted to prohibit swimming off the island, "as any seal can plainly foo."

Callahan's was routinely visited by aliens, time travelers, parallel dimension tourists, and just about every other sci-fi cliche there is.  Many of these stories were published in Analog SF magazine.

The series also inspired the newsgroup news://alt.callahans -- SusanDavis