It began simply enough, with a TV overheard out an open window on a summer’s evening in the mid-1980’s on the suburb fringes of St. Louis. Over the buzz of the lawn trimmer, I heard snatches of a Monty Python rerun and, as I wound up the extension cord and swatted early mosquitoes, I thought I heard an exchange that went as follows:

“Not?”

“Yes.”

“A Zanzibar invertebrate?”

“A Zanzibar invertebrate.”

“A Zanzibar invertebrate!”

“Indeed.”

If there was more, it was lost behind my brothers’ shrieks and howls of laughter. I looked in the window in time for a blurred glimpse of British comedians in pith helmets batting each other with taxidermied ostriches.

By the time I got inside, the show was over and something else was on.

For a couple days, I wondered what I’d missed. Then, I forgot about it.

A few years later, I went to college and lived down the hall from a clutch of python-philes. Hardly a conversation went by without some chance word being taken as an oblique cue, and off they’d go, launching into elaborate, multi-voiced recitations.

One night they compiled an alphabetical list of every python sketch.

“Hey,” I said, “You missed the whole Zanzibar invertebrate thing.”

I did my best to describe what I remembered, and we were up until three while they spun theories as to why they’d never seen it -- which season it might have been an outtake of, which lost episodes or rehearsal tapes had been aired during PBS fund drives.

Two years later, in a different dorm’s dining room basement, I overheard a different group of enthusiasts. The words had shifted slightly, but there was no mistaking it: “A Zanzibar vertebrate?” “Indeed.” And much laughter.

I wound up behind one of them in the next day’s breakfast line. I asked for more details -- did he know what the ostriches had to do with it? He didn’t. He hadn’t seen it any more than my old friends had.

It was years before I heard of it again, mentioned in passing on some documentary on British comedy. I checked the web, and found full scripts, annotated with analysis, sketches, links to fan reenactments. I searched Google, YouTube and Wikipedia with every term I could think of -- no sign of the original footage. I think I know why: it never existed.

Whatever I misheard, the sketch didn’t exist until the fans began rehearsing and repeating it.