I usually rough-record new songs and then "filter" them through my family before inflicting them on anyone else. When I played "Lowestoft Rock" to my 17-year old daughter for the first time, at the end she looked at me incredulously and asked "What is the first line of the chorus again, Dad?".
So I repeated the line for her: "So what's to become of the large beamers now", referring to an alternative name for trawlers, but clearly a word she was not familiar with. "Thank God for that" she said, "I thought you were singing 'penis' instead of 'beamers'!".
She was right - the rough recording was very ambiguous around that word. So when the time came to record the song properly, I paid particular attention to that line. The result: I kept dissolving into laughter at that point for the first 5 times or so, and nobody could understand why, until I told them...