Broken ice-cream machines and wrongly-added jalapenos could not have bothered customers at a McDonald's outlet in New Jersey last week, as they had much bigger fish (or should we say rats?) to fry.

A man released a giant, white, menacing-looking rat at the joint, to the horror of customers who were peacefully relishing their Big Macs. 

The man was allegedly angry about his McDonald's order being messed up, which led him to take this extreme step.

The rat, which was confined to a clear plastic box, evidently excited by its newly-found freedom, jumped right into the midst of the crowd, sparking chaos. 

A video of the prank has since gone viral on social media, leaving netizens amused, horrified and grossed out by the rat.

Since being shared by Facebook user Fe Bugout, the video has garnered over 5,000 comments and more than 2.5 lakh views.

The video shows an unidentified man entering a busy McDonald's outlet with a young child and a rat in a pet carrier. The child asks the man to let him hold the rat, but in vain.

As the man enters the restaurant, customers who realise that he is about to set the rat free look dumbfounded. 

Once freed, the rat explores its surroundings, causing turmoil as people trample each other, jump over chairs and tables and frantically make a dash for the exit.

Soon after the video ended, "the rat exited the restaurant through the front door," a McDonald's spokeswoman told NJ.com.

"The safety of our customers and the cleanliness of our restaurants are our top priorities," said Celest Quintana, the owner/operator of the franchise, in a statement.