Paul McCartney has opened up about secretly slipping swear words into some of The Beatles' biggest tracks.
The global music icon has let slip that he would use Scouse slang to slip in words without music execs knowing what was being said.
Paul, 78, said: "There was a thing in Liverpool that us kids used to do, which was instead of saying ‘f*** off’, we would say ‘chicka ferdy!’
"It actually exists in the lyrics of The Beatles song Sun King.
"In that song we just kind of made up things, and we were all in on the joke.
"We were thinking that nobody would know what it meant, and most people would think, ‘Oh, it must be Spanish,’ or something."
The superstar added: "But, we got a little seditious word in there!
When the song was release, John Lennon laughed it off as a "kind of childish teasing between young people on the street".
Lennon said at the time: "“We just started joking, you know, singing ‘quando para mucho.’
"We just strung any Spanish words that sounded vaguely like something.
"And of course we got ‘chicka ferdy’ in. That’s a Liverpool expression.
"Just like sort of... it doesn't mean anything to me but ‘na-na, na-na-na!’"
Writing in his memoir before untimely his death, The Who bassist John Entwistle recalled another crude game McCartney and Lennon would play during their time on the road.
Entwistle admitted to overhearing the band adding a string of offensive words during a concert.
After discovering they couldn't be heard over the noise of the audience they dropped a string of explicit words.
Entwistle said: "Soon, the four of us were crying with laughter at the words they were singing and which only we were able to pick up on,.
"It’s been a hard day’s c**k … I wanna hold your c***.'"