According to family legend, one afternoon my Scottish grandfather announced that the County Surveyor would be calling in. My grandmother became quite excited, arranging for a cake and scones to be baked and the best china set out in the drawing room. She thought he'd said the Countess of Ayr.
I've come across a similar story since, so perhaps it was apocryphal. Such cases where something is misheard have been called 'Mondegreens', from a line in the old Scottish ballad 'The Bonnie Earl of Moray'. It runs, "They have slain the Earl of Moray and laid him on the green", but is misheard as "They have slain the Earl of Moray and Lady Mondegreen." Others call them 'Gladly's', after the line from the hymn, "Gladly, my cross-eyed bear".
The propensity for headlines to be misread is similar, although I'm not sure if there is a name for that. Favourites include the wartime, 'Eighth Army Push Bottles Up Germans' and 'Monty Flies Back to Front'. I like the one about the explorer, 'Vivian Fuchs off to Antarctica'. More recently there was, 'Never Withhold Herpes From Loved One', and 'Kids Make Nutritious Snacks'.
And there are the accurate but blindingly obvious - as in 'Plane Too Close to Ground, Crash Probe Told'.
Which all reminds me of Robin Waterfield's frequently-repeated claim (see June 15, 'Biting the Lager Queue') that his ancestor discovered Uranus.