An Invercargill man who threw his half-eaten burger at a restaurant manager, complaining it contained too much lettuce, was told he had issues by the judge when he appeared in the Invercargill District Court yesterday.

Rory McLeod Burfoot, 20, was convicted of assault when he appeared before Judge Christina Cook.

Police prosecutor Sergeant Rob Mills said Burfoot and an associate entered the Invercargill McDonald's restaurant on December 7, intoxicated and carrying alcoholic drinks.

The manager told the pair they were not allowed to drink alcohol in the restaurant and the drinks were put outside, Mr Mills said.

Burfoot then walked up to the counter, complaining there was too much lettuce in his burger, and demanded his money back.

The manager asked the men to leave, but Burfoot resisted, verbally abusing him, Mr Mills said.

After requesting six times that the two leave the restaurant, the manager called the police, and Burfoot threw his half-eaten burger at him. The burger hit the manager on the forehead.

Police arrived, finding Burfoot belligerent and unable to offer an explanation for his behaviour, Mr Mills said.

Burfoot, representing himself in court, said he genuinely believed his burger contained too much lettuce.

He admitted throwing his burger at the manager and not leaving when asked, but disputed verbally abusing the manager.

The whole incident was "just a little bit of a slip-up", he said.

Judge Cook said Burfoot clearly had issues with alcohol and his general demeanour. "This man is an employee of a restaurant.

He's just trying to do his job. There is no, and can be no, justification for you throwing your burger at him." She sentenced Burfoot to 100 hours' community work.