They then shone bright lights onto the barrier draw results and from across the other side of Circular Quay, the numbers of the race horses displayed on the heritage building were obscured.
Racing New South Wales pitched the idea to promote the upcoming world's richest turf race, the TAB Everest.
The protest is in response to the NSW government's decision to override an earlier ruling by the chief executive of the Opera House, Louise Herron, who did not want to project horse names and branding on the building's sails.
With 2GB breakfast host Alan Jones at the centre of the storm - for stridently advocating for the use of the Opera House to promote the Everest Horse Race and calling upon its CEO Louise Herron to be sacked - Goa has produced boards offering him free use of its "real billboards".
It comes following a Racing NSW decision to cancel a live barrier draw for its multi-million dollar race The Everest, citing security risks amid ongoing public outrage at plans to project the results onto the Sydney Opera House.
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"Gave her a big talking to. you're allowed to project on there, that's the biggest billboard in Sydney, mate".
Sleeping Giants Oz issued a statement to AdNews, saying: "Sleeping Giants Oz fully supports the action against allowing the Everest Event to go ahead at the Opera House and applaud everyone who supported the petition".
"It is the view of the Heritage Council that the use of the Opera House for the commercial advertising of this event is completely unsatisfactory and is an inappropriate use of this significant heritage place that is valued by many around the world", he said.
"The Opera House management has approved exemptions under the Heritage Act to make these types of decisions", the spokesman said. The Sydney Opera House initially rejected the proposal but a state official overruled and allowed a revised 10-minute projection of the ad for October 9.
This morning on his radio show that targets "most people to die of natural causes in the next 12 months" (nice one SBS) Jones non-apologised to Ms Herron for his vile spew.