Liberal Democrat leader Sir Vince Cable fluffed the key line in his closing speech at the party conference.
Journalists had been briefed Sir Vince would speak of Leave campaigners having an “erotic spasm” over a hard Brexit.
Sir Vince grimaced as he stumbled over the phrase, saying “exotic spresm” instead.
Watch: James Whale gives Vince Cable an elocution lesson
The mistake overshadowed the rest of his speech, where Sir Vince tried to reach out to Leave voters, saying that he understands their anxieties and that wanting to manage immigration is not racist.
Demanding another EU referendum, the Liberal Democrats leader attacked hardline Brexiteers by saying they got an “erotic spasm” from the thought of breaking with Brussels, whatever the cost to the economy.
And Sir Vince hit out at Labour leader Jeremy Corbyn for hiring "hard-left boot boys" to do his dirty work "intimidating" colleagues.
Sir Vince said: "I don't accept the idea that it is some form of racism to want immigration to be managed like other parts of the economy.
"To dismiss all Brexit voters as racists is simply wrong and utterly counter-productive."
‘Respected jobs to crap jobs’
Sir Vince said parts of the country felt "left behind" and the Lib Dems had to combat the false perception that overall immigration had damaged wages.
"Deindustrialisation, globalisation ... all these 'tions' that were supposed to represent progress have often meant a move from skilled and respected jobs to crap jobs - from certainty to insecurity."
Insisting that Brexit was not inevitable, Sir Vince attacked Tory hardliners, saying: "To the 'true believers' - the fundamentalists - the costs of Brexit have always been irrelevant.
"Years of economic pain justified by the erotic spasm of leaving the European Union. Economic pain felt - of course, not by them - by those least able to afford it."
Sir Vince called for Labour to topple Mr Corbyn if he did not back a new referendum.
"If Jeremy Corbyn will not say 'I will support a people's vote and I will fight Brexit', Labour members should wave him goodbye."
Sir Vince also insisted Prime Minister Theresa May does not believe in Brexit.
He said: "She is dutifully delivering a policy she doesn't really believe in - failing in negotiations, losing public support - and all to appease a dwindling group of angry people in her party who will denounce her as a traitor, whatever she comes up with."