The Beatles are renown as perhaps the most experimental group ever to reach a large, mainstream audience. However, they got their start as conventional pop idols. One of their hits from their pop idol period was “Do You Want to Know a Secret.”
Many aspects of “Do You Want to Know a Secret” set it apart from other Beatles song. One unique aspect of the song is that its original version featured a toilet flushing. Another is that is was one of the early tunes sung by George Harrison.
John wrote “Do You Want to Know a Secret.” He recorded a demo of the track in a restroom at a German nightclub. He felt this was the only place quiet enough for him to record the demo. At the end of the demo, he flushed the toilet – an encapsulation of his cheeky humor. Sadly, the demo is lost forever.
Source: cheatsheet.com