These pre-agreed words or signals, when uttered, mean that everything must stop immediately.

Source: https://thefrisky.com/using-bdsm-equipment/

The tune by Paulo de Carvalho was the pre-agreed signal to start an armed coup, and for rifle-toting military to rise up against a fascist dictatorship.

Source: https://www.theguardian.com/tv-and-radio/2023/may/13/did-this-pop-banger-just-trigger-an-armed-coup-the-wild-revolutionary-politics-of-eurovision

While the agency has rejected spot bitcoin ETFs, it has approved bitcoin futures ETFs, which track agreements to buy or sell bitcoin at a pre-agreed price.

Source: https://cyprus-mail.com/2023/08/31/understanding-grayscales-victory-in-spot-bitcoin-etf-case/