My Dad worked at a factory for years, and every Christmas they held a kids' party. There was always some entertainment, including singalongs. One year, we sang "The Marrow Song". It went like this:
Oh, what a beauty
I've never seen one as big as that before
Oh, what a beauty
It must be two foot long or even more
And such a lovely colour
So nice and round and fat
I never thought a marrow
Could grow as big as that.....
I took it at face value then. Years later I heard Kenneth Williams sing it on the radio, and realised just how utterly filthy it was. An old music hall song, apparently. Mind you, KW could have made the phone book sound filthy which is why I liked him so much.