[Hack]

I recall hearing an interview with Al Capp 40 or 50 years ago and he said that the name was pronounced by making a noise with your mouth. He then demonstrated using the sound made when a noise like breaking wind is made.

[Eric in the Ozarks]

He was a regular on the Jack Parr Tonight Show.
Yeah, that's how old I am.

[UnklGene]

It’s called the old “raspberry.”