1a interjection — Politics
fuck or fuck off.
Type: 1. Origin — The link between fuddle duddle and the meaning 'fuck off' is attributed to former Canadian Prime Minister Pierre Elliot Trudeau (see the 1971 quotation). Trudeau most likely coined the term as a spontaneous alteration of fuddy duddy, an 'old-fashioned, fussy person' (see COD-2, s.v. "fuddy duddy"). Trudeau was accused of mouthing the obscenity fuck off by members of the opposition party during a House of Commons debate in 1971. After the incident, Trudeau famously stated that he "didn't say anything", but he admitted to moving his lips in derision (see CBC reference). Pressed with follow-up questions about the words he mouthed, Trudeau offered fuddle duddle.
From that point on, fuddle duddle has been associated with fuck off in Canada. Fuddle duddle is sometimes used as a direct replacement for fuck, such as fuddle duddle around (see the 1978 quotation), "what the fuddle duddle" (see the 2007 quotation) or "fuddle duddle you" (see the 2009 quotation). The term carries cultural salience as a widely known euphemism. As seen in Chart 1, the term is almost exclusively used in Canada.
See also COD-2, s.v. "fuddle duddle", which is marked "Cdn euphemism". Not listed in ITP Nelson (Gage-5, as a school dictionary, would not list near-taboo words such as this one).
1b n.
nonsense.
Type: 1. Origin — See meaning 1. Fuddle duddle is a nonsense word that Trudeau apparently coined on the spur of the moment. It appears to have been generalized to mean "nonsense".
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Chart 1: Internet Domain Search, 11 Jun. 2014