The tone of debate in the House of Commons hit a low for the second time in two weeks Tuesday when an NDP MP from Quebec used the F-word during question period.

Asking a question about the Trans Mountain pipeline, Romeo Saganash, a First Nations NDP MP from Abitibi—Baie-James—Nunavik—Eeyou, accused Prime Minister Justin Trudeau of not caring about the rights of Indigenous peoples.

"When the prime minister says that this pipeline expansion will be done no matter what, and his minister adds that Canada will not be able to accommodate all Indigenous concerns, what that means is that they have decided to wilfully violate their constitutional duties and obligations," Saganash told the House.

"Mr. Speaker, sounds like a most important relationship doesn't it? Why doesn't the prime minister just say the truth and tell Indigenous peoples that he doesn't give a fuck about their rights?"

The Quebec NDP MP was questioning the government on the Trans Mountain pipeline 2:05

Speaker Geoff Regan immediately stood and told Saganash that, as an experienced member of the House of Commons, he should have known better. He invited the MP to apologize and withdraw the word.

"Mr, Speaker, what is happening is so insulting, it makes me so angry, but I do withdraw the word," Saganash said.

Last week, Prime Minister Justin Trudeau was forced to apologize for using unparliamentary language in his reply to a Conservative question about military procurement.

Trudeau was attempting to turn the question around and accuse the Conservatives of failing to provide the Canadian military with the tools it needs, instead using soldiers "for photo ops ... every damn time."

Regan did not intervene to ask the prime minister to apologize or take back his words, but Trudeau stood at the end of question period on a point of order to apologize.

"Mr. Speaker, it was brought to my attention that in an outburst of enthusiasm I may have used a word that was unparliamentary. I withdraw that word and apologize to anyone who was offended."

Prime Minister Justin Trudeau was responding to a question from Manitoba Conservative James Bezan 1:02

That wasn't the first time Trudeau used unparliamentary language in the House.

In 2011, before becoming Liberal leader, Trudeau swore at then Environment Minister Peter Kent.

The commotion began when NDP MP Megan Leslie was questioning Kent about Canada's withdrawal from the Kyoto Protocol.

Kent suggested that Leslie should have been in Durban, South Africa, for the recent UN climate change conference, which prompted howls from the opposition benches because opposition MPs were banned from being part of Canada's delegation at the conference.

Kent's response was interrupted by heckling, and Trudeau could be heard shouting, "You piece of shit" at the environment minister. Trudeau later apologized for the language.

"I lost my temper and used language that was most decidedly unparliamentary and for that I unreservedly apologize and withdraw my remark," Trudeau said after question period had concluded.

WARNING: Graphic language: Liberal MP Justin Trudeau apologized to the House Wednesday after he called Environment Minister Peter Kent a 'piece of shit.' 2:34

Trudeau's words to Kent led inevitably to comparisons with a notorious Commons incident involving his father.

In February 1971, Conservative MP John Lundrigan accused former Liberal prime minister Pierre Trudeau of mouthing an obscenity at him.

A fellow Tory MP, Lincoln Alexander, later told reporters, "The first [word] started with the letter F, the second word the letter O."

When pressed outside the Commons by reporters, a clearly perturbed Trudeau made a joke about "lip-readers ... crying to mama" and denied saying "anything" before finally admitting, "Yes I moved my lips" — and uttering a phrase for which he became famous.

"What is the nature of your thoughts, gentlemen, when you say 'fuddle duddle' or something like that?"

Prime Minister Pierre Trudeau swears he didn't use any four-letter obscenities. 2:14

The use of rude or unparliamentary language by public officials hasn't been confined to the House of Commons lately.

Conservative MP Michelle Rempel aimed a number of insults and strident language at Liberal Veterans Affairs Minister Seamus O'Regan via Twitter Tuesday.

The Opposition critic for immigration called O'Regan a "ridiculous coward" and a "disgrace" in a tweet that used the word that most recently got Trudeau in trouble: "damn."

Rempel has not issued an apology.

You’re a ridiculous coward. You know damn well I’m talking about Christopher Garnier, a cop killer who isn’t a veteran, but who you continue to give Veterans benefits even though he’s never served a day in his life. Do your damn job and revoke his benefits. You are a disgrace. <a href="https://t.co/aFI9duwBJd">https://t.co/aFI9duwBJd</a> —@MichelleRempel

A review of Hansard, the official record of parliamentary debates in Canada, reveals that the F-word has been dropped in the Commons on two other occasions since January 2001.

The first instance was in 2003, when Bloc Québécois MP Michel Gautier in 2003 rose on a point of order to accuse the finance minister of saying "fuck off." And in 2014, the NDP's Isabelle Morin said in the Commons that "Canadians have been fucked over by the government."

According to the Library of Parliament, variations on the F-word were spoken at committee 25 times during the same period.