Some people at a Wisconsin rally jeered after U.S. President Donald Trump suggested they sing ‘O Canada’ while he was speaking about the trade dispute between the two countries.

For the third year in a row, Trump skipped out on the White House Correspondents Dinner -- a high-profile event traditionally attended by the president and political reporters.

But instead of attending this year, Trump held a rally in Green Bay, Wis., Saturday night. In-between unscripted rants about potential 2020 Democratic Party challengers and shots against the media, he mentioned Canada, one of the biggest trading partners of the United States.

At around 18 minutes into his remarks, he told a crowd a supporters that Canada had been taking “big advantage of your agricultural products.”

And in his classic, unfocused stream of consciousness, Trump takes a slight aside to say, “Let’s sing ‘O Canada,’ we love the song.”

People in the crowd can be heard booing and jeering at the suggestion to sing Canada’s national anthem. Trump doesn’t address the boos and continues speaking about U.S. dairy farmers and the high duties they had to pay Canada.

Prime Minister Justin Trudeau had a fairly well-documented “bromance” with former U.S. President Barack Obama -- including one awkward three-way handshake with him and former Mexican president Enrique Peña Nieto.

But Trump’s relationship with Canada and Trudeau has been fairly frosty since Trump took office in 2016.

Throughout the past three years, Trump has taken shots at Canada over trade, a U.S. trade representative called Canada a national security threat after the U.S. levied steep tariffs on Canadian steel, and, regarding trade, that “Canada does not treat us right.”

No official in the Canadian government has commented on the remarks yet.