John Lennon sung part of The Beatles classic â€˜Yellow Submarineâ€™ through a condom to protect himself from an electric shock.
The legend was trying to create an underwater singing effect and originally going to take more hazardous avenues to achieve the effect.
But teenage engineer Geoff Emerick came up with the idea to cover the microphone.
He explains: "John wanted to be recorded underwater to simulate being in a submarine. He was like that. He didn't realise the implications of that.
"I thought to get a bottle of water and put a microphone in the water and get him to sing to that and then I realised there was a huge amount of electrical current going through the microphone.
"So to protect the mic, Mal Evans (Beatles road manager) had a condom in his bag and I put the mic in the condom and put it in the bottle.
"John could've blown up because there was 240 volts running through this thing. It was part of some lead vocal but they never used it. I'm sure it's somewhere," quotes contactmusic.