What is the origin of the phrase 'to blow smoke up someone's arse'?

Many BBC History Magazine readers will be fans of Patrick O’Brian’s novels, and will know that his Napoleonic-era naval captain Jack Aubrey constantly uses ‘smoke’ as a verb meaning to uncover a deception, as in ‘smoke out’.

But in all the slang dictionaries we’ve consulted, we can’t find any association between smoke and posteriors before the Second World War, by which time the tobacco bellows would have long been forgotten. The second part of the phrase was probably added to ‘blow smoke’ just to coarsen it, and it may well have originated with the British or, more likely, American armed forces.

There are other explanations. Our favourite goes back to the First World War when British troops would hold a papier-mâché dummy over the trench parapet to attract the fire of enemy snipers and determine their position. For added realism, the fake Tommy would have a cigarette in its mouth, and a soldier crouching below him would blow smoke out of it through a tube.

Attractive though the theory is, the dummies never had rears to blow through, as a complete figure wasn’t needed. The dummy was usually just a head with a tin helmet, and it would have been held up on a stick.

• Read next | When were cigarettes invented? A brief history of smoking

Answered by Eugene Byrne, author and journalist

This article was first published in BBC History Magazine in 2010