Entertaining children armed with a stack of traditional nursery rhymes may conjure an image of perfect innocence.
The original meanings of some rhymes have been lost
But one amateur historian claims those favourite verses sound more suited to the local pub than the playroom.
Bawdy sexual, religious and political themes dominate traditional verses like Jack and Jill and Oranges and Lemons,
according to author Chris Roberts.
The real meanings and metaphors behind 24 common rhymes are explained in his book Heavy Words Lightly Thrown.
Librarian Mr Roberts, 37, was researching material for his London walking tours when he uncovered the story behind Oranges and Lemons.
'Slur on country folk'
The playground chant is in fact a rude wedding song, with references to "a candle to light you to bed" describing a bride tempting her new husband.
In other family favourites, Baa Baa Black Sheep is an attack on taxation, and See Saw Marjorie Daw, is "essentially a slur on country folk".
Mr Roberts says Jack and Jill is a cautionary tale of pre-marital hillside sex, with a metaphorical breaking crown.
Goosey Goosey Gander meanwhile focuses on the moral campaign against Tudor prostitution - goose being a euphemism for streetwalker.
Mr Morris said his examples drew on the original meanings of the rhymes, which have faded through time.
"Some of the meanings were quite straightforward and there's a historical record of them," he said. "Others were harder to pin down and I deal with the theory in the book."
As for the next generation of nursery rhymes, Mr Roberts suggests they will come up from the terraces.
"Like folk songs, football chants have anonymous authors but thousands of people know them and sing them. They have no beginning, they just erupt," he said.
"And, yes, I do know people who croon football songs to their children at night."