Fuddle duddle
Fuddle duddle is a euphemistic substitution for "fuck" or "Fuck Off", whose most famous use was by former Canadian prime minister Pierre Trudeau.
Trudeau caused a minor scandal when opposition MPs claimed that he had mouthed the words "fuck off" to them in the House of Commons in February 1971. Pressed by journalists, Trudeau later unconvincingly stated he may have said (or mouthed) "fuddle duddle or something like that."
The phrase then took on a humorous connotation of that event for Canadians.