Let's call out the MAFS poo toothbrush incident for what it really is: Abusive behaviour.

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Last night, Married At First Sight aired something that should never have been shown on television.

A man named David used his (former? fake?) wife’s toothbrush to clean poo from the toilet bowl. He scrubbed it into the faeces, rinsed the toothbrush in the bowl and returned the toothbrush for Hayley to use.

In an interview with Mamamia before the toothbrush saga aired on Wednesday night, Hayley said before she was accused of kissing Michael, she and David were already sleeping in separate rooms.

The MAFS experts have a lot to answer for. Post continues below video.

“I couldn’t actually say we were a couple, it was over but that doesn’t justify what happened by any means – that’s really important to say,” she said.

After her kiss with Michael, David took his anger out by going approximately 200 steps too far, messing with her toothbrush.

Called out on it at the dinner party, David said it was just a prank and his mates have done worse to him because practical jokes have “no limit”.

But… David. This isn’t a joke.

Cheating is, without a doubt, a terrible thing to do to someone. Whether David and Hayley were living in separate apartments or not, he was within his rights to feel betrayed.

But to respond to it in such a way was not only childish and petty, but could be considered dangerous and abusive under NSW law.

First of all, ingesting faecal matter can cause a person to become sick with illnesses such as Hepatitis.

Other bacteria commonly present in faeces include Campylobacter, E. coli and salmonella, all of which can cause nausea, vomiting, fever, fatigue, diarrhea and abdominal pain and cramping.

But also... It can get much worse.

Dr Brad McKay told Mamamia the bacteria in poo is very different from the bacteria in your mouth.

"If the bacteria in your poo was the same as the bacteria in your mouth, your breath would smell like sh*," he said.

"Coating your toothbrush in excrement isn't advisable because toothbrush bristles can push faecal bacteria into the gaps between your teeth and gums. If you're lucky, the infection will remain in your mouth and only cause a gum infection (gingivitis). But if you're unlucky, the bacteria will enter your bloodstream, can infect your heart valves, or you can die from sepsis."

This means, legally, Hayley could have a case.

The NSW Crimes Act 1990 includes a section on "Using poison etc to endanger life or inflict grievous bodily harm".

1)  A person is guilty of an offence if—

(a)  the person administers to another person, or causes another person to take, any poison, intoxicating substance or other destructive or noxious thing, and
(b)  the poison, intoxicating substance or other thing endangers the life of, or inflicts grievous bodily harm on, the other person, and
(c)  the person intends to injure, or is reckless about injuring, the other person.
Maximum penalty—Imprisonment for 10 years.

Another section, "Using poison etc to injure or to cause distress or pain", does away with the requirement that "the poison intoxicating substance or other thing endangers the life of, or inflicts grievous bodily harm on, the other person" and carries a maximum penalty of 5 years imprisonment.

Speaking to Mamamia, Nicholas Stewart, Partner at Sydney firm Dowson Turco Lawyers said Hayley would be within her rights to allege David endangered her health.

"My view is David, by exposing Hayley’s toothbrush to a noxious thing, namely a used toilet bowl containing human faeces, he may have committed an offence under s 39 or s 41 of the Crimes Act 1900 (NSW) or a similar provision of another state or territory’s law," he explained.

"In respect of s 39 the prosecution would have to prove (a), (b) and (c) and there would be some question as to whether a toilet containing faeces is an 'other destructive or noxious thing' that 'endangers life' and there was sufficient intention of David to injure Hayley or there is sufficient evidence that he was reckless about injuring her.

That is criminal law and the elements of the offence must be proved beyond reasonable doubt. That is a high threshold and I am not suggesting that David, without a doubt, is guilty of the offences above."

Beyond that, Stewart said Hayley could have reason to allege a crime of intimidation.

Abuse is, by definition, any action that intentionally harms or injures another person.

"So, acting in a way that causes Hayley to fear harm and intimidation is a factor that could lead to a police officer or a person (such as Hayley) seeking an Apprehended Violence Order (AVO) to protect her," Stewart explained.

On Wednesday, Hayley told Mamamia she wished she went to the police during filming but was told not to.

"I really should have. That's one of my biggest regrets. I got told not to go to the police, that production would deal with it," she said.

"When he went into there unsupervised, he wrecked my clothes, took some of the food on the bench and filmed the toothbrush incident.

"I've spoken to the police about this, it’s classified as a form of physical abuse. It can endanger your person and you can get Hepatitis A."

Stewart said if production did prevent her from reporting the incident to police, it could be alleged it was complicit in David's actions.

"I'm not suggesting a crime has been committed, but there are potentially elements for investigation (and those elements must be proven beyond reasonable doubt). There are certainly circumstances that may warrant Hayley seeking protection under an apprehended violence order, in which case the police or a court would consider Dave’s actions and the circumstances of them.

It seems to me there are all kinds of actions that Hayley could take here, and a report to the police would be appropriate."

Speaking on news.com.au’s podcast Not Here to Make Friends, her former 'husband' admitted his actions were "really childish".

“About three days after the cheating scandal happens, I’ve heard nothing from Hayley and I’m in a really dark place… I still had her room key, and that’s when I did something really childish,” he told James Weir, Samantha X and Kerri Sackville.

Having listened to the 41-minute episode, Hayley said he was still not taking "accountability for what actually happened".

"Although he’s saying the act was very childish, I feel as though he’s not bringing himself into play. It’s really a half-arsed way of saying sorry," she said.

Mamamia reached out to David for comment, but at the time of publication, he had not responded.