In 1974, Frank Zappa played a concert in Helsinki, which was
released in 1988 as (surprise!) The Helsinki Concert on You Can't
Do That On Stage Anymore Vol 2. Right when the bizarre piece
Building A Girl ended, a member of the audience demanded from the
band that they play the song Whippin' Post.
Zappa (mocking the loudmouth):
Okay, just a second. Do you know that? (pause) Oh, sorry, we don't
know that one. Anything else? (pause) Hum me a few bars of it,
please. Just show me how it goes, please. Just sing me Whippin' Post
and then maybe we play it with you.
The guy went "uh-uh-uh" (which could as well have been from Beethoven's Fifth Symphony).
Thank you very much. Judging from the way you sang it, it must be a
John Cage composition, right?
This incident must've irritated the band so badly that they
got the beginning of the next song - Montana - not as perfect as Zappa had expected. Zappa
stopped them after a couple of bars.
Hold it. Hold it! We can't possibly start the song off like
that. Good Lord, that's inexcuseable. What happened to you
last night? (pause) George has a tape of it? Okay, we'll
use that in the second show. Ready? Montana...
Wait a minute... Whippin' Post... no... Montana...
They started again, this time Chester Thompson of Genesis fame messed up the drum part early in the song and, again, Zappa stopped them.
It's too fast for you?
He counted to four at half the speed. This time they got it right, they
played the song without further interruption, and Zappa replaced parts
of the lyrics with references to Helsinki (instead of Montana)
and whipping posts. That's the Whippin' Floss version of
Montana. Zappa actually started playing a cover of Whippin' Post
later in his career, which can be found on Them Or Us (1984) and
on the album and video versions of Does Humor Belong In Music?. The
album version has a guitar solo by Dweezil Zappa, the other versions
have great solos by Frank. IIRC, all the versions are sung by Bobby
Martin, who played keyboards and saxophone on the 1984 tour and
has a great white blues voice.