It takes a brave musician think they can improve on a Beatles song - let alone take the Michael.

But John Lennon was no ordinary musician and you can forgive him for re-tooling one of his own earlier hits with a couple of added words.

However, Do You Want To Know A Secret might not have reached No.1 in the US and No.2 in the UK with its rudely reinvented lyrics.

Lennon's cheeky sense of humour is brought to the fore again in The Think For Yourself sessions, recorded during the completion of the pop masterpiece album Rubber Soul, which celebrates its 50th anniversary this month.

The rip-roaring album sessions put the Fab Four right up against the wall with just a month straddling October and November to record an album for release at Christmas.

They wrote seven of its 14 classic tracks in just one week, reports Rolling Stone.

(Image: Michael Ochs Archives/Getty Images)

It's no surprise that they used a little extra stimulation to get them through it, with marijuana and booze among their instruments of choice.

And in that febrile hot-house of drink, drugs and furious creativity even going to the toilet was a chance to produce.

When John Lennon pops to the little Beatles' room between takes he sings the hookline of Do You Want To Know A Secret, which featured on their album Please Please Me, and was originally sung by George Harrison.

Ever the competitor, John thinks he can do it a little better and decides to change the words.

Perhaps feeling that the 1963 song now felt a little innocent, he lends it a more adult bent, clicking his fingers as he sings "Do you want to hold a penis? Doo-wah-ooo!" as you can hear on the audio clip above by scrolling to 2:45.

It's not the first time old examples of Lennon's humour have come to the fore though, and not always in such innocent cheeky fashion.

Earlier this year, fans were left shocked by disturbing footage of Lennon mocking disabled people.

The Beatles legend was an inspiration to many, but over the years his darker side has been revealed - and TV show It Was Alright In The 1960s has brought him back under fire.

In an old clip from a live performance with the Fab Four, Lennon is seen pulling faces and making exaggerated movements in an offensive manner.

The video resurfaced on the Channel 4 show this week, and it has prompted a disappointed reaction from viewers as they were reminded of the star's views.

MORE: John Lennon's dark side from domestic violence and emotional abuse to mocking disabled people

Taking to Twitter, one viewer wrote: "John Lennon mocking the disabled is disturbing to say the last #AlrightInThe60s (sic)"

Another added: "#johnlennon's distasteful learning disability impressions I saw on #itwasalrightinthe60s tonight would never have been OK. #beatles (sic)"

Despite Lennon's sick sense of humour being discussed by fans of the years, many were still outraged by the video.

One tweeted: "itwasalrightinthe1960s anybody who's read a bit about The Beatles knows that 'Saint' John Lennon had a cruel 'humour' about disabled people".

"That clip just confirmed what I thought #AlrightInThe60s," another said. "John Lennon was just a complete c***! You don't take the p*** out of disabled ppl (sic)"