He had a similar message for the police call taker who informed him officers were on the way to the coastal spot.
"If they rark me up my flatmate will cop it," the defendant said.
Officers found Prattley shortly after and quickly discovered he was capable of following through on the threats.
The defendant, perched on the cliff top, picked up the victim as police closed in.
"I will throw him over if you come any closer," Prattley said.
Eventually, Prattley put his flatmate down and was arrested.
Counsel John Westgate said his client had no memory of the dramatic incident because of his alcohol use and was at a loss to explain what was behind it.
He accepted it was "fairly disturbing behaviour" but stressed his client took full responsibility for his actions.
The court heard the victim had taken a compassionate stance on the matter.
He said he had no issues with Prattley when he was sober and simply wanted him to get the help he needed.
Judge Kevin Phillips said the defendant had a lengthy criminal history, featuring convictions for intimidation, violence, kidnap and arson.
Prattley had received sentences with a rehabilitative focus in the past and they had not resulted in lasting change, the judge said.
The behaviour in November was "alarming in the highest extent" and had come shortly after Prattley had been released from a previous prison term for assault and strangulation.
Added to that, Prattley had little support in the community, the judge noted.
Prattley was jailed for 14 months.
