An Invercargill man with an extensive criminal background didn't believe robbing a dairy was an offence because the shopkeeper handed the money over.

Brandon Antony McGregor, 20, and Phillip John O'Brian, also 20, appeared before Judge Michael Turner for sentencing in the Invercargill District Court on Thursday for the aggravated robbery of the Crinan St dairy on November 2 last year.

They made off with $1000 but McGregor was caught 30 minutes later because the shopkeeper took note of his neck tattoos and police found him at an associate's house.

Crown solicitor Mary-Jane Thomas said she accepted O'Brian had a history of intellectual impairment but that he chose to self-medicate with legal highs.

On November 2 last year, the pair walked from a friend's house to the dairy and waited until no one was around before entering.

O'Brian confronted a 53-year-old dairy worker and demanded money while brandishing a knife. McGregor stood to one side also with his knife showing. They left the dairy with about $1000 from the till and walked to a friend's house where they changed clothes.

Judge Turner said McGregor had an extensive criminal record, a sense of entitlement and did not see the robbery as an offence because the woman handed over the money.

McGregor said if it had been him he would have had a gun behind the counter and refused to hand over the proceeds, the judge said.

Defence lawyers for both McGregor and O'Brian told the court their clients had limited intellectual capacity.

O'Brian's lawyer Fergus More asked for a merciful sentence because of his client's vulnerability.

The court was told O'Brian suffered a brain injury as a baby and throughout his life had been targeted by bullies and was easily manipulated.

O'Brian did have success with Special Olympics and at one point had been selected to represent New Zealand basketball squad, the court was told.

McGregor was sentenced to three years and 10 months' jail. He was sentenced to three months' jail, to be served concurrently, for two charges of burglary on October 26 and 28, and ordered to pay $89.98 reparation.

O'Brian was sentenced to two years and three months' jail and ordered to pay $24 reparation. For dangerous driving on October 18 last year he was sentenced to one month's jail, to be served concurrently, and disqualified from driving for 12 months.