The Orangeville Meat Co (OMC) in south-west Sydney's Gregory Hills has thrown down the gauntlet in no uncertain terms.

The OMC Big Mouth Burger Challenge will require contestants to finish a massive two-kilogram burger in under 40 minutes.

George Assoni, the OMC owner, said he didn't think anyone would be able to finish the mammoth meal.

"Our biggest burger at OMC, The Fatboy, weighs 450 grams and some people struggle to finish that," he said.

"I'd like to think someone will finish but I don't think they will."

The Big Mouth Burger is made with a custom-made 600 gram milk bun, almost 1.5kg of Angus beef plus tomato, lettuce, onions, pickles and three kinds of sauces.

The challenge will be held on Thursday, February 20.

It costs $40 a person to enter and all entrants will be required to sign a waiver.

All contestants will receive an OMC Big Mouth Burger Challenge hat, runner-up prizes include cup holders and t-shirts.

The winner will receive a trophy, t-shirt, a $100 food voucher, their picture on the OMC wall of fame and, most importantly, bragging rights.

Mr Assoni said the competition was an idea from burger lovers across Macarthur.

"Customers would come in and tell us that we should have a burger eating compeitition - some of them would just ask when we would be having one," he said.

"So it was really the customers who came up with this idea.

"We have the best burgers in western Sydney - so I thought we should give the burger eating challenge idea a go."

Only 10 people will be able to take part in the Big Mouth competition.

Mr Assoni urged people to sign up before all the spaces were taken.

"We have five people who have already signed up," he said. "It's going to be a great night.

"We will also have prize giveaways on the night for people who come to watch - it's all about having some fun."