Gurning is a British word for pulling a grotesque face. An from the land of unusual sporting events, they have even made a competition out of it - the World Gurning Championship.
Gurning competitions are thought to have originated in 1297 at the Egremont Crab Fair, in the UK, named after the crab apple, which are pretty sour. It makes sense then that as part of 'Crab Fair' in this part of the world they hold face pulling competitions to see who can make the ugliest face.
This must be easier for some people, though they make it even easier to make a funny face by requiring you to also wear a horse collar at the same time. Gurning through a horse collar is known as "gurnin' through a braffin'. A typical gurn involves projecting the lower jaw as far forward and up as possible, and covering the upper lip with the lower lip
The competition is held in mid-September each year. To get an idea of what it involves, check out this gurning video. There are competitions for men, ladies and juniors. England's best-known gurner is Peter Jackman, who won the world championship four times from 1998, with a face called the "Bela Lugosi".
Elsewhere in the world, there is the similar Mr. Ugly Competition in Zimbabwe, which requires a little more than pulling an ugly face, they are after men who are 'naturally' ugly!