The best fart joke in the world ever

So, have raced through Julian Barnes' Before She Met Me in the last few days. Delicious, as ever, but also disturbingly odd. But it does have a fart joke that almost had me in tears on the Victoria line t'other morning. To whit:

Once, Jack had rung up and insisted that he help him choose a squash racquet. Graham protested that he’d only ever played squash three times – once with Jack, when he’d been sent scurrying around the court towards a heart attack – but Jack refused to accept his disclaimers of authority. They met in the sports department of Selfridges, and though Graham could quite plainly see the squash and tennis racquets over to their left, Jack dragged him off on a tour of the whole floor. After about ten yards, though, he suddenly stopped, did his pre-fart pivot so that his back was slanting towards a row of cricket bats, and sounded off. As they walked on, he muttered sideways to Graham,
‘The Wind in The Willows.’