"I don't take any s***," Dane Cowley said, explaining punching a man who ended up in hospital for a month with a brain bleed.
Cowley, 21, was sentenced in the Wanganui District Court on Wednesday to seven months' home detention for wounding with intent to injure.
His victim had helped break up a fight between Cowley and another person at Marton Hotel on April 5 last year.
When the bar closed at 11.45pm, Cowley followed him on to the street, grabbing the neck of his shirt from behind.
Cowley then landed a punch that forced his victim to the ground. Noticing the man was unconscious, Cowley attempted to rouse him before returning to the hotel and his associates and leaving the scene.
Meanwhile, an ambulance was called and medics treated cuts to the victim's head and lip.
Confused and disoriented, he was later admitted to Wanganui Hospital and diagnosed with a bleed on his brain. The man was later transferred to Kenepuru Hospital and not discharged until May 7, 2012.
For a further six months, he was not allowed to drive and was unable to work full-time.
Judge David Cameron said Cowley's criminal history indicated he had an alcohol problem, having had two convictions for driving with an excess breath-alcohol level, one for breaching a liquor ban and another for wilful damage.
Cowley had shown "very little" remorse, which Judge Cameron said was perhaps best indicated by what he told his pre-sentence report writer: "I don't take any s***."
"That really highlights the fact you're a person that hasn't come to grips with reality," Judge Cameron said.
Cowley was sentenced to seven months' home detention, with six months of post-detention conditions, ordered to pay $1000 for emotional harm and given a warning under the three-strikes law.