A gurn or chuck is a distorted facial expression, and a verb to describe the action. A typical gurn might involve projecting the lower jaw as far forward and up as possible, and covering the upper lip with the lower lip, though there are other possibilities.
The English Dialect Dictionary, compiled by Joseph Wright, defines the word gurn as "to snarl as a dog; to look savage; to distort the countenance," while the Oxford English Dictionary suggests the derivation may originally be Scottish, related to "grin." In Northern Ireland, the verb "to gurn" means "to cry," and crying is often referred to as "gurnin'." Originally the Scottish dialectical usage refers to a person who is complaining.
Gurning contests 
Gurning contests are a rural English tradition. By far the most notable is that held annually at the Egremont Crab Fair, which dates back to 1267 when King Henry III granted the fair a Royal Charter. The origins of the gurning competition itself are unclear, and may not be so old, although it was described as an ancient tradition by local newspaper the Cumberland Paquet in 1852.
The competitions are held regularly in some villages, with contestants traditionally framing their faces through a horse collar — known as "gurnin' through a braffin'." The World Gurning Championship takes place annually at the same crab fair in Egremont, Cumbria. Those with the greatest gurn capabilities are often those with no teeth, as this provides greater room to move the jaw further up. In some cases, the elderly or otherwise toothless can be capable of spectacular gurns covering the entire nose.
Peter Jackman became England's best-known gurner, winning the world championship four times, beginning in 1998 with a face called the "Bela Lugosi." He made numerous TV appearances, including an appearance on the BBC programme They Think It’s All Over.  He had his teeth removed in 2000 to make his features easier to manoeuvre.
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