WATCH: Trudeau references his father after allegedly swearing in the House

"What is the nature of your thoughts, gentlemen, when you say you move your lips in a particular way," said Trudeau to reporters.

Trudeau here referenced his father, Pierre, after he was accused of using a four-letter obscenity. "What is the nature of your thoughts, gentlemen, when you say fuddle-duddle or something like that?" said Pierre to reporters in 1971.

Trudeau allegedly used the word after a question from the Conservatives that Trudeau called "dangerously close" to disinformation.

The vulgarity was not caught by microphones in the House, though it was apparently heard by the first two rows of Conservative MPs across the aisle from the Liberals.