It's a case involving a $60,000 debt, a mysterious debt collection "boss" with the ability to collect money from bikie gangs, and a heavily-muscled "polite" stand-over man.

Christopher John Butler is on trial in the ACT Supreme Court accused of making a demand accompanied by a threat to endanger another man's health, safety or physical well-being.

But Butler has pleaded not guilty, and his lawyer Kamy Saeedi has suggested his client did not make a threat to endanger.

The court heard Butler first entered the Fyshwick renovation business on March 2 last year with a message for the owner.

The man's wife, who was in the shop at the time, said Butler "looked like the Incredible Hulk, only not green".

"When I say this, I mean he was like a bodybuilder, and very muscular," the wife later told police.

The alleged victim wasn't there, however, and the court heard Butler returned the next day and the day after that.

The pair finally spoke at length - the conversation taped, and this morning played to the court.

In a conversation lasting about an hour, Butler apologised repeatedly for worrying the alleged victim's wife and told the man he "seems like a decent bloke".

He also described himself as "the first step" and said if a 6 foot 7 man named Junior arrived at the man's business, he should run.

Butler was also recorded describing his unnamed boss as a debt collector with decades in the business, and the ability to recoup owed money from bikie gangs.

He added some people protested their innocence, until they "get an arm cut off, or a leg broken, and the next day they pay up".

Acting Justice John Nield has reserved his decision.