You know there's an election in the air when the wheels start to fall off in question time.

And so it was on Monday, when the Treasurer twice forgot the day of the budget, and the Deputy Prime Minister stunned colleagues and commentators alike with a spectacular rant about giving herpes to fish (yes, really).

"The budget I will hand down tonight ..." Scott Morrison initially declared, a full 29 hours before he was due to deliver it. Fast forward half an hour and suddenly "we're two days from the budget"; a slip-up that prompted guffaws from across the chamber, and even a raucous round of applause.

Never one to concede a point, the Treasurer dug in. "Monday, Tuesday - two days!" he insisted, noting that despite the imminent delivery of the nation's pre-eminent economic document, Labor had not asked him a single question about the budget (they were directed to the Prime Minister instead).

But there was plenty of time for a Dorothy Dixer on one of the budget's lesser-known line items: a $15 million project to eradicate pesky carp from Australia's rivers.

As we are only too well aware, nothing animates Barnaby Joyce more than the prospect of seeking vengeance against an animal. But nothing prepared the House for the tirade that was about to be unleashed against "the rabbit of our waterways".

"It's incredibly important because we are afflicted in this nation with these disgusting mud-sucking creatures," the member for New England began, with a mischievous and knowing nod towards the opposition benches. "Bottom-dwelling, mud-sucking creatures for which the only form of control is a version of herpes."

Mr Joyce has been on something of a herpes tour. He announced the policy up in Tamworth at the weekend, telling reporters it was the only time he was happy to discuss the venereal disease. But he seemed rather chuffed with his routine on Monday, bellowing into the microphone as his face turned a shade of red one might associate with the very ailment itself.

"We don't want to have to deal with caaaaarp! No, we don't want to deal with caaaaarp. We've to get rid of the caaaaarp!" he yelled, imbuing the word with the throaty growl of a lawnmower caught on a tree root. The country's second-in-charge soon turned his mind to disposing of the 2 million tonnes of carp that might be produced by such a massacre.

"We'll have to bury the caaaaarp. We'll have to put it outside, put it in the paddocks, bury it, put it underground," Mr Joyce roared, seeming to lose his train of thought as the backbenchers behind him struggled to contain themselves. By the time he sat down, "carp" had almost eclipsed the banal "jobs and growth" as the most tortured term in question time.

Good thing there are only 60 days of this carping to go. Or perhaps if you're Scott Morrison, 61.