The man accused of setting a friend alight said he should have just "stopped, dropped and rolled" and the matter would have just been a joke instead of a serious incident.

Matt-Dillion Shannon took the stand in his own trial this morning. Shannon, now 18, is on trial in the Napier High Court.

He has pleaded guilty to a charge of causing grievous bodily harm with reckless disregard but not guilty to a charge of causing grievous bodily harm with intent.

The Crown claims Shannon was celebrating his 17th birthday on August 12 last year.

Shortly after midnight the Crown claims he poured petrol over a 16-year-old friend with the intent to cause grievous bodily harm. He said the idea came from a similar stunt seen on Jackass movies.

This morning Shannon, who was a petrol station attendant at the time, said he poured a shot glass full of petrol over the victim who he claimed was asleep on Shannon's bed. He then set it alight with a cigarette lighter.

"I thought he'd wake up, get a fright and roll about until the flame was extinguished and he'd be fine," Shannon said.

"He just didn't do what I thought he would. He just jumped up and ran around. If he'd stopped, dropped and rolled it would have just been a joke instead of a serious incident," he said.

He said others at the party were yelling "do it" and "light him on fire".

He said he had no intention of causing serious harm to the victim and he had not told others to hold him down, as claimed by the victim.

He also said the victim was probably held down for only five seconds, not the twenty seconds he claimed, and denied the petrol was poured from a petrol container as the victim stated.

Under cross-examination Shannon said there were no signs of burning to his bedclothes or the walls of his bedroom.

Yesterday the jury heard from the victim that he had not been drinking as he was getting over glandular fever.

The victim said he heard Shannon say, "Get him", then three people grabbed him and held him down.

"He [Shannon] was laughing. He picked up the petrol can and was pouring it over me," he said. "It felt wet and warm. I thought it was just water. When I figured out it wasn't, I freaked out."

Shannon then pulled a lighter from his pocket. "I said, 'Matt, please don't do this.' I was begging him."

He said the three people, whose names are suppressed, held him down for about 20 seconds until he broke free.

"It was like nothing you could imagine you'd ever feel," he told police.

"It was the most excruciating thing you could imagine, times 10," he said.

- © Fairfax NZ News