What is the definition, usage, and etymology of "flarn"?

meaning

Urban Dictionary has a definition:

A polite way to describe curse words.

"You can't say no filth flarn filth flarn filth"
"Have a coke and a smile, and shut the fuck up!"

Given the hashtags on the entry, it seems likely that Eddie Murphy coined this word. The IMDb lists these quotes (warning: language):

[Bill Cosby has called Eddie to complain about bad language in Eddie's act]
Eddie Murphy: Now I can't have no 'curse' show, I mean I gotta throw in a few jokes in between the curses, I can't come out and go "Hello! Filth flar'n filth, motherfucker, dick, pussy, snot, and shit. Good night! Suck my dick!"

Eddie Murphy: [as Bill Cosby] Yoouuu cannot say filth flarn filth flarn filth in front of people!
Eddie Murphy: And I said, "I never said no filth flarn filth! I don't know what you're talking about! I'm offended that you called! Fuck you!" And that's when Bill got raw on me!

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