McDonald’s has come up with a secret trick to help stop drunks fighting while they line up for a late night Big Mac.

McDonald’s is looking for more civilized diners who don’t want to have a parking lot brawl, and is attempting to calm customers so they don’t have the urge to fight people who may have pushed in line or spilled their Coke.

The chain tried playing classical music over its speakers during the late hours to see if it impacted the way drunk diners behaved, and it worked.

Glasgow in Scotland was the first city to implement the classical music trick and Stockport, England, tested it out two years ago when violence at the restaurant was rife.

Diners at McDonald’s restaurants in Gloucester and Liverpool, in the UK, can now scoff down fries and burgers while listening to the classical tunes of Bach and Mozart.

A McDonald’s Australia spokeswoman told news.com.au playing classical music in restaurants was not company policy, but individual restaurants had done it in the past.

Last year, a drunken brawl at an Adelaide McDonald’s restaurant led to jail time for one of the men involved and a video went viral in 2015 showing young men spraying security guards with fire extinguishers at a restaurant in Newcastle, about 100 miles from Sydney.

An insider at the McDonald’s restaurant on King Street told the Newcastle Herald there were growing concerns about late night violence at the fast food outlet.

The source claimed staff feared for their safety as drunk and drug-affected diners turned on them. Some of the out-of-control behavior included fights, barging past the counter to help themselves to food, and vandalism.

A McDonald’s UK spokesperson told The Mirror: “We have tested the effects of classical music in the past and played it in some of our restaurants as it encourages more acceptable behavior.”

“Typically classical music is played from early evening onwards, and in some cases, on certain nights in a small number of restaurants.”

Duke University’s Dr. Kevin Laber found classical music calmed people as it released pleasure-inducing dopamine and repressed the release of stress hormones.