boat on the water
mast in the sky

The story:

Most of us were headbangers except for one bloke called Siggery. Mishearing this lyric at a loud party one night, he was singing the wrong version at the top of his lungs. The next time the chorus came round, someone whipped down the volume, and Siggery gave it all he'd got with the wrong words. Deathly silence followed for a few seconds, followed by utter pandemonium. I laughed so hard my face went into spasm.