A man jailed for violence told his victim he was sorry, but it was "a Mongrel Mob thing", before beating him unconscious, Masterton District Court heard.
Anthony Sene Fa'afo'i, 20, was sentenced to 22 months in prison for injuring with reckless disregard for safety, and two breaches of community detention.
Judge Bill Hastings said Fa'afo'i and two others had been drinking at a Masterton hotel and had left together "late in the evening".
The group had stopped at an intersection and Fa'afo'i "told the victim you were sorry and that it was a Mongrel Mob thing", the judge said.
"You then proceeded to hit him about the head, causing him to lose consciousness".