Warrick Pearson (20), of South Otago, pleaded not guilty to two counts of indecent assault but a jury found him guilty of one, following a Dunedin District Court trial in June.
Judge Kevin Phillips yesterday sentenced the defendant to four months' home detention but added: ''I think you thoroughly deserve to go to prison.
''Your attitude, Mr Pearson, for a 20-year-old, can only be described as absolutely appalling,'' the judge said.
''You're arrogant. You believe the laws don't apply to you and you consider orders and rules are for people other than yourself.''
Pearson had been drinking in a car with friends on May 12 before they ended up meeting another group of associates in Pak'n Save car park, South Dunedin.
The victim, who was among the second group, was not interested in talking to the defendant.
''She made her views in relation to you very, very clear,'' Judge Phillips said.
''She told you to f... off.''
But Pearson continued his advances, eventually grabbing the woman's bottom.
At trial, she said he did so ''very firmly''.
The victim wrote a statement detailing how she had lost friends over the incident.
''I hate what he did to me. He kept grabbing me like he could do whatever he wanted to.
''He took no notice of me or what I was saying to him,'' she said.
The judge described the act as ''totally demeaning''.
''While I accept it was over clothing, it was in a public arena and in front of her friends.''
Pearson was supposed to be on bail at a Balclutha address but contravened the order by moving to Central Otago.
While there, he added two more counts of receiving to his growing list.
He was found with a stolen meat pack and a child's quad bike at the Roxburgh house at which he was staying.
The court heard Pearson had previous convictions for burglary, theft and breaching sentences.
''You are a thoroughly dishonest young man,'' Judge Phillips.
But counsel Andrew Dawson said he had seen a change in his client in the past few months.
It was partly due to the fact the defendant's partner was three months pregnant.
''He realises he needs to pull his socks up,'' Mr Dawson said.
Pearson was looking for farming work to support his growing family, the court heard.
As well as home detention, he was sentenced to six months' post-detention conditions to address his mental-health and alcohol issues.
Pearson was ordered to pay $400 to the quad bike owner and a previous sentence of community work that had hung over him would remain in place, Judge Phillips ruled.
