I guess they felt like singing the word "pal," zipp. But that's the blues where lyrics are often extemporaneous.
The only formal music training I ever had was blues guitar with Ian Buchanan. He was taught blues guitar by Reverend Gary Davis and Brownie McGee and in turn taught John Hammond, Jr. and Jorma Kaukonen this style of Delta Blues. I studied with Ian Buchanan from 1972 to 1974.
Thanks for the Ian Buchanan song. Was he Canadian, American or British? I can't find much info about him on the net.
As for the Beatles and Kansas City, as I've already said, they were following Little Richard's second arrangement. They replaced the sax solo with George's guitar solo and followed through with the lead singer and the answering chorus. This was in no way extemporaneous. In fact they had a very tight routine that runs all the way from the Cavern to the McCartney clip from 2014 with very little variation.
Did Paul misunderstand Little Richard's 'chile' ? Did he think 'pal' and 'gal' were more fun or more American-sounding?
For whatever reason Paul and the chorus always sing more or less the following :
Hey Hey Hey Hey
Hey Hey Hey Hey
Hey Baby
Hey Baby
Wooh, now gal / girl
Now gal
I say now pal
Oh pal,
Now now now tell me baby, what's been wrong with you ...