--- description: A gag app that allows you to say "Yo" to your friends is now being repurposed to potentially save lives. title: The "Yo" App's Role in the Israeli-Gaza Conflict image: https://static.time.com/v3/assets/bltea6093859af6183b/blt16eb00db487f5280/69869bb7adae44cc67544257/156023705.jpg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 ---  * [World](/section/world/) ## World Update your preferences in [Account Settings](/account/preferences/) Close # 'Yo' App Retooled to Alert Israelis of Missile Attacks by [Salima Koroma](/author/salima-koroma/) ## Salima Koroma Update your preferences in [Account Settings](/account/preferences/) Close Jul 14, 2014 10:08 PM CUT  Smartphone touchscreen Smartphone touchscreenGetty Images by [Salima Koroma](/author/salima-koroma/) ## Salima Koroma Update your preferences in [Account Settings](/account/preferences/) Close Jul 14, 2014 10:08 PM CUT The “Yo” app was developed as a joke. Download the app, tap on a friend’s name, and they’d get a message from you saying “Yo.” It’s that simple. In fact, the app was created in eight hours and released on April Fools’ day just so people would know it was a gag. But Yo has a new application that’s no laughing matter. Developers in the Middle East are using the app to warn Israelis of possible attacks from rocket fire; users following the handle “RedAlertIsrael” will get a “Yo” at the same time the country’s sirens go off. One person’s gag app is apparently another’s survival tool. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/2983226/yo-app-israel-missile/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/2983226/yo-app-israel-missile/"},"headline":"'Yo' App Retooled to Alert Israelis of Missile Attacks","datePublished":"2014-07-14T22:08:21.000Z","dateModified":"2026-04-13T08:02:46.215Z","description":"A gag app that allows you to say \"Yo\" to your friends has been repurposed to potentially save lives","url":"https://time.com/2983226/yo-app-israel-missile/","keywords":["Tech","Israel","Gaza and the West Bank","World","Hamas"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt16eb00db487f5280/69869bb7adae44cc67544257/156023705.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Salima Koroma","jobTitle":null,"url":"https://time.com/author/salima-koroma/"}],"articleSection":"World","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt16eb00db487f5280/69869bb7adae44cc67544257/156023705.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"156023705","caption":"156023705","creditText":"Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/world/","name":"World"}},{"@type":"ListItem","position":2,"item":{"@id":"https://time.com/2983226/yo-app-israel-missile/","name":"'Yo' App Retooled to Alert Israelis of Missile Attacks"}}]}] ```