Phoenix, I'd forgotten that one, but found myself singing along, as I must have done aged 10 or so. I'd no real notion what balls were, but I had an inkling and knew it was 'rude' so loved it.
Others posting here must have had a mum like mine - we had number two's, poo was a banned word. She hated anything "coarse" when we were children, and insisted on manners, politeness at all times. She mellowed with age, and also with the enjoyment she got from our use of expletives. My dad was taught to sing the following age 4 or 5, by his older cousins:
Shit bugger damn
some bloody buggers gone and shat our sam
Dad's aspirant parents were so not amused.
One of my favourites from my childhood and early teen years was the use of the word 'common' to describe women of a certain type. It was never explained to me, I absorbed it's meaning as I heard it used,sniffily, by my mother and aunts to describe - well, their brother's wife really.