This comes from a sub-section of the original BBC Radio version of The Hitchhiker’s Guide to the Galaxy. It’s a bit intricate, so here’s the whole thing:

“May (or may not)…” pops up all over in my lexicon.

“Some of you may (or may not) remember the story I told…”

Although on re-hearing it, I admit a fondness for “Representatives of the Amalgamated Union of Philosophers, Sages, Luminaries, and Other Professional Thinking Persons.” Let alone, “(W)e demand rigidly defined areas of doubt and uncertainty!”