When I was about 6, I thought that when a song fades out, the effect is created by the band performing on the back of a truck, which then drives away from the microphone.
I was also highly confused by songs which had the same person's vocals played over the top of each other, wondering how the hell it was possible to sing two things at the same time. When my mum told me that it was done by a mixer, I imagined a mixer to resemble a big washing machine.
A childhood belief about songs

others believed things like this
- I thought the 'dubbing mixer' on TV credits was the person in charge of stirring the make up for the actors.— Clive
- i used to believe that our ansering machine was the washing machine and that it could talk
— tamara - I used to believe that if I put my arm in the washing machine while it was going that it would rip off.— Hannah
- Once I used to believe that a engineer is a person who drives railway engine.— Gaurav Jain
- i used to believe Gunsn Roses' vocals were from an old lady!!!! — Vivika
- last time when the television was on i thought the people were performing in it -.-
— irritated kid