One of the BMJ’s technical editors taught me about mondegreens recently. They’re members of the same genus as malapropisms, dogberryisms, and eggcorns, where a similar sounding word or phrase is substituted for the original, altering its meaning but producing something more or less grammatical and that makes at least some sense. The word was coined by an American writer, Sylvia Wright, who when very young misheard the lines of a Scottish ballad read to her by her mother. “They hae slain the Earl of Moray and they laid him on the green” became, in her childish mind, “They hae slain the Earl of Moray and Lady Mondegreen,” and it stayed that way until she encountered a written version of the verse many years later.

As so often happens after something is first pointed out, I started seeing mondegreens all over the place. “Give peas a chance”—a spraycan graffito spotted on a motorway bridge—brightened up a tedious journey, although …