BEN Black was having "a bad day" when he overtook a Mercedes-Benz driver then slammed on his brakes and stopped, blocking the road.
Black got out of his Holden Nova holding a metal bar and walked over to the Benz driver yelling abuse.
Bundaberg police say more than 40 vehicles had been stopped before Black went back to his car and drove off.
Before he got back in the car he yelled at the Benz driver "I've got a f-ing screaming kid in my car".
No threats were made.
Benjamin Patrick Black, 30, a dad of four, pleaded guilty in Bundaberg Magistrates Court to causing public nuisance at 4.25pm on Thursday, August 10; and driving without due care and attention.
Magistrate Neil Lavaring convicted and fined Black $900 but did not disqualify his licence.
Prosecutor, Senior Constable Grant Klaassen said the incident happened when Black, with a child, was driving west on Bargara Road in an 80km/h zone.
The Benz driver had been two vehicles ahead of Black with a line of traffic behind him.
At the approach to the Burnett Heads Road intersection Black crossed double lines and overtook.
Black crossed a painted island and narrowly avoided a concrete traffic island in the manoeuvre.
Snr Cnst Klaassen said Black hit the brakes heavily and stopped, blocking traffic behind him.
Black got out onto the road with a metal bar in his hand and yelled abuse, also saying "why do 70 in an 80 zone?".
Snr Cnst Klaassen said Black, when interviewed by police, stated he believed the Mercedes-Benz Sprinter driver was intentionally varying his speed.
Black then made the decision to overtake and stop "to prove a point".
"He says there was no excuse for his actions, saying he was having a bad day," he said.
Legal aid lawyer Nick Larter said the behaviour appears to be out of character for Black .
"On this day he was under an unusual amount of stress," Mr Larter said.
"His other daughter had been hospitalised and he was on his way to see her, and the other child in the car was somewhat distressed.
"It could well have resulted in something far more serious.
"His behaviour outside of the car did not escalate to threats or damage property."
And although separated, Black had shared responsibilities for four children and needed his licence.
Magistrate, Neil Lavaring said he had seen much worse, where people had been killed.
However, Mr Lavaring said the facts were somewhat concerning.
He said he would not disqualify his licence and fined Black $900 - sent to SPER.