The idea behind the much-talked-about YO app, which allows users to send messages to each other saying nothing more than “yo”, is that the word can be interpreted differently depending on the context.
But this is a context no one was expecting: it is now being used by Red Alert, an Israeli missile notification service, to warn civilians of incoming strikes from the Palestinian border.
Called RedAlertIsrael, it combines information from the Israel Defense Force and the Homefront Command to provide real-time warnings of mortars being fired by Palestinian militants.
YO was invented earlier this year as an April Fools' joke by an Israeli living in San Francisco, but since then it has grown to be extremely popular, with two million people now using the basic messaging service worldwide.
The creators of RedAlertIsrael, Ari Sprung and Kobi Snir, are trying to tap into its wide user base within Israel so that their alerts can reach more of the people who may be at risk of attack. The alerts are designed to work in conjunction with other, more detailed messages sent by Red Alert.
Having previously been described by critics as a gimmick and "accelerating the decline of humanity", YO has now proved its worth in the eyes of many Israelis.
Anouk Lorie, editor in chief at an Israeli tech blog called NoCamels, told the BBC: "Red Alert is a potentially life-saving app for a large number of Israelis who have only 15 seconds to find cover from the dozens of daily incoming rockets, so I'm not sure that 'Yo!' is the appropriate word to see pop up on mobiles."
“Perhaps seeing 'Yo!' on your screen feels less distressing than the loud siren that is otherwise the default on Red Alert,” she added.
Use of the app follows a recent escalation in tensions between Israel and Palestine, and a resulting increase in attacks from both sides. But the app is currently only available to Israelis, with Palestinians turning to Twitter hashtags to keep informed of possible strikes.